Stimulation of mitogenesis by the epidermal growth factor (EGF) operates through a pathway involving the receptor, the small G‐protein Ras and protein kinases of the MAP kinase cascade. It is proposed that two of the critical steps of that pathway utilize localization of components to the plasma membrane where Ras is located: recruitment of the nucleotide exchange protein Sos to the phosphorylated EGF receptor via a complex with the SH2/SH3‐containing protein Grb2 and recruitment of the protein kinase Raf to activated (...) Ras. Moreover, it is then proposed that Raf associates with the cytoskeleton at the membrane as it is being activated. Other signaling elements, including class I receptor kinases, nonreceptor tyrosine kinases and tyrosine phosphatases, are known to function at specific cellular sites. These observations have led us to propose that localization of signaling components, and particularly sites at membrane‐microfilament interfaces, play critical roles in cellular regulation. (shrink)

I denne teksten blir følgende spørsmål tatt opp til drøfting: Er det å ta medisinsk teknologi i bruk for å selektere et døvt barn mer etisk problematisk enn det motsatte; å bruke teknologien for å sikre seg et hørende barn? På bakgrunn av fire premisser konkluderer jeg med at både seleksjon for døvhet og for hørsel er tilnærmet like etisk problematisk. De fire premissene er 1) at seleksjonskriteriet sykdom eller skade bør erstattes av autentisitetsbetraktninger, 2) at døve og hørende har (...) samme potensial for autentisk livsutfoldelse, selv om det ikke kan avvises at døvhet kjennetegnes ved manglende hørsel, 3) at seleksjon innebærer fravalg av liv som har autentisk potensialitet enten som døv eller hørende, og 4) at dette fravalget involverer en etisk kostnad. Konklusjonen har enkelte andre implikasjoner og en restproblematikk som belyses avslutningsvis. (shrink)

Peirce’s system may be identified as one of a family of “organic memory” theories which flourished during the period in which he developed it, especially in the Monist journals which published much of his late work. “Organic memory” theories were vigorously opposed in their own day and are remembered in our own, if at all, only in connection with discredited theories such as racial memory and Lamarckian inheritance. When read in the context of their own time, however, “organic memory” theories (...) stand revealed as among modernity’s first attempts at a still-unrealized, post-nominalist re-foundation of science. Being thus closely related to Peirce’s own project both in time and in spirit, they deserve to be understood on their own terms. The synthesis of these theories in the book Das Gesetz der Serie (1919) by the Austrian biologist Paul Kammerer (1880-1926), a prominent representative of organized Monism's European branch, provides insight into the systematic unity of the various aspects of Peirce's thought, especially the close relationship between pragmatism and what is now called “emergence.”. (shrink)

The concepts of love and business do not seem to match very well, despite attempts to operationalize love as agape or neighborly love. In line with the emerging literature, this contribution uses a profane and analytical approach to agape as an ‘Agenda for Growth and Affirmation of People and the Environment’. Within this agenda we define agape as ‘the commitment to the well-being and flourishing of others’ and operationalized it to measure the concept in a substantial sample of 420 medium-sized (...) and large companies in The Netherlands. At the core of the research lies the question whether and to what extent companies, represented by senior managers and members of the works council, are committed to the well-being of their employees. This article analyses the concept of agape and its application in a business context and presents the results of a survey. The results show that, on average, respondents report that their organization is committed to employees’ well-being in line with the organization’s values. Though not the aim of agape, since organizations that apply the concept reap tangible business benefits from it, the concept becomes suitable to a wider range of businesses. (shrink)

. In his work The Cosmos in Light of the Cross physicist and Lutheran pastor George L. Murphy extends the religious rationales of Dietrich Bonhoeffer and Eberhard Jüngel to argue specifically for a nonreligious, scientific study of and appreciation for the world. In doing so, Murphy offers a clear and coherent theology of the cosmos within the bounds of piety alone. Like Calvin and Schleiermacher before him who strove to stay within these bounds, Murphy shares their endpoint of a practical (...) theology—that is, faithful reflections that will encourage wise and faithful existence. In doing so, Murphy has written a brilliant and extraordinarily readable account of a chiasmic cosmos. He also quite practically and indeed pastorally offers suggestions for how the God of that cosmos may be not only understood but also worshiped and adored. (shrink)

Humanistic management emphasises the importance of respecting humanity in and through meaningful work within organisations. In this paper we introduce a Levinasian approach to organising. Levinas argues that the Other appeals to us and allows us to take responsibility towards the Other – i.c. an employee, a customer, a supplier, etcetera. In this article our focus is on employees. By taking the Other as a starting point of his reflections, Levinas helps to transform the organisation and management of work and (...) humans in business organisations. Based on the concept of alterity and becoming susceptible to the appeal that comes to us through what Levinas refers to as the ‘face of the Other’, we argue that the philosopher calls for ‘an agapeic turn’ to management and organisation. This turn means that the focus on the well-being of the employee – and the needs, interests, ideas, and expectations as perceived by him or her – should be at the core of organising. As a result, this paper calls for an increased focus on self-determination and self-organisation to allow the Other both voice and control over her or his behaviour, actions and contributions to the outputs and outcomes of one’s organisational unit. Through our focus on a Levinas approach, we concretize and deepen the traditional understanding of agape, making it more relevant to our functioning in a business setting. As a result, agape is introduced as an analytical concept that guides the structuring and the effectuation of human interaction in and through organisations. (shrink)

The Jedi are “keepers of the peace.” Just as they protect the galaxy, Jedi are called upon to keep the peace within themselves by aligning their wills to the Force. This requires self‐restraint, abstinence from worldly pleasures, a virtue‐driven mindset, incorruptible fearlessness, and total belief in following the will of the Force. The principles of the Jedi Order closely mirror the “hard life” maxims of a school of philosophy known as Stoicism, represented by the slave‐turned‐philosopher Epictetus. For both Jedi and (...) Stoics, philosophy is a way of life, not just a subject for study. A central claim of Stoic ethics is that only virtues and virtuous activities are good, and only vices and vicious actions are evil. A Jedi's strength of mind has greater value than the ability to execute a Force push. The ultimate goal for Jedi is to decipher the will of the Force and conduct themselves accordingly. (shrink)

In discourses on digitization and the data economy, it is often claimed that data subjects shall beownersof their data. In this paper, we provide a problem diagnosis for such calls fordata ownership: a large variety of demands are discussed under this heading. It thus becomes challenging to specify what—if anything—unites them. We identify four conceptual dimensions of calls for data ownership and argue that these help to systematize and to compare different positions. In view of this pluralism of data ownership (...) claims, we introduce, spell out and defend a constructive interpretative proposal: claims for data ownership are charitably understood as attempts to call for theredistributionof material resources and the socio-culturalrecognitionof data subjects. We argue that as one consequence of this reading, it misses the point to reject claims for data ownership on the grounds that property in data does not exist. Instead, data ownership brings to attention a claim to renegotiate such aspects of thestatus quo. (shrink)

We study some generalized notions of cohesiveness which arise naturally in connection with effective versions of Ramsey's Theorem. An infinite set A of natural numbers is n-cohesive (respectively, n-r-cohesive) if A is almost homogeneous for every computably enumerable (respectively, computable) 2-coloring of the n-element sets of natural numbers. (Thus the 1-cohesive and 1-r-cohesive sets coincide with the cohesive and r-cohesive sets, respectively.) We consider the degrees of unsolvability and arithmetical definability levels of n-cohesive and n-r-cohesive sets. For example, we show (...) that for all n ≥ 2, there exists a Δ 0 n+1 n-cohesive set. We improve this result for n = 2 by showing that there is a Π 0 2 2-cohesive set. We show that the n-cohesive and n-r-cohesive degrees together form a linear, non-collapsing hierarchy of degrees for n ≥ 2. In addition, for n ≥ 2 we characterize the jumps of n-cohesive degrees as exactly the degrees ≥ 0 (n+1) and also characterize the jumps of the n-r-cohesive degrees. (shrink)

Making good decisions in extremely complex and difficult processes and situations has always been both a key task as well as a challenge in the clinic and has led to a large amount of clinical, legal and ethical routines, protocols and reflections in order to guarantee fair, participatory and up-to-date pathways for clinical decision-making. Nevertheless, the complexity of processes and physical phenomena, time as well as economic constraints and not least further endeavours as well as achievements in medicine and healthcare (...) continuously raise the need to evaluate and to improve clinical decision-making. This article scrutinises if and how clinical decision-making processes are challenged by the rise of so-called artificial intelligence-driven decision support systems (AI-DSS). In a first step, this article analyses how the rise of AI-DSS will affect and transform the modes of interaction between different agents in the clinic. In a second step, we point out how these changing modes of interaction also imply shifts in the conditions of trustworthiness, epistemic challenges regarding transparency, the underlying normative concepts of agency and its embedding into concrete contexts of deployment and, finally, the consequences for (possible) ascriptions of responsibility. Third, we draw first conclusions for further steps regarding a ‘meaningful human control’ of clinical AI-DSS. (shrink)

This paper examines three proposals on the difference between the complex and the simple view about personal identity: Parfit’s original introduction of the distinction, Gasser and Stefan’s definition, and Noonan’s recent proposal. I argue that the first two classify the paradigm cases of simplicity as complex, while Noonan’s proposal makes simplicity and complexity turn on features whose relevance for the distinction is questionable. Given these difficulties, I examine why we should be interested in whether a position is complex or simple. (...) I describe two purposes of having a distinction, and show that extant accounts of the complex versus simple distinction fail to serve these. I argue that unless we find a satisfying account of the difference between complex and simple positions, we should not frame discourses on personal identity in these terms. (shrink)

This paper examines three proposals on the difference between the complex and the simple view about personal identity: Parfit’s original introduction of the distinction, Gasser and Stefan’s definition, and Noonan’s recent proposal. I argue that the first two classify the paradigm cases of simplicity as complex, while Noonan’s proposal makes simplicity and complexity turn on features whose relevance for the distinction is questionable. Given these difficulties, I examine why we should be interested in whether a position is complex or simple. (...) I describe two purposes of having a distinction, and show that extant accounts of the complex versus simple distinction fail to serve these. I argue that unless we find a satisfying account of the difference between complex and simple positions, we should not frame discourses on personal identity in these terms. (shrink)

In his article ‘Better Communication Between Engineers and Managers: Some Ways to Prevent Many Ethically Hard Choices’1 Michael Davis analyzes the causes of the disaster in terms of a communications gap between management and engineers. When the communication between (representatives of) both groups breaks down, the organization is in (moral) trouble. Crucial information gets stuck somewhere in the organization prohibiting a careful discussion and weighing of all (moral) arguments. The resulting judgment has therefore little (moral) quality. In this paper I (...) would like to comment on some of Michael Davis’s interesting and thought-provoking insights and ideas. A company which implements Davis’s recommendations at least shows some sensitivity to organizational moral issues. But it might miss the point that moral trouble can also result from a common understanding between managers and engineers. Organizational members sometimes tend to be myopic with regard to safety issues. This paper: 1. describes different meanings of safety Managers and engineers, as Davis mentions, are sometimes willing to compromise quality, but do sacrifice safety. It is my contention that safety—in the sense of putting people’s lives on the line—will always be compromised, and that the discussion is about the ways to negotiate the risks./li 2. focuses on a shared understanding of the situation and its implications for safety Using examples from a case study I did on behalf of a commercial airline,2 I will try to show that it is not always the communications gap between managers and engineers which poses a risk to the stakeholders involved, but a common understanding of the situation. 3. focuses on a ‘timely concatenation of both active and latent failures’ as a cause for accidents I will argue that—in spite of our efforts to strengthen ethical consciousness and organizational practices—there will always be accidents. They are part of the human condition, since we cannot completely control the complexity of the situations in which they occur. One can, however, make them less costly. (shrink)

Recent contributions to discussions on paediatric cochlear implantation in Norway indicate two mutually exclusive doctrines prescribing the best course of post-operative support for a child with cochlear implants; bilingually with sign language and spoken language simultaneously or primarily monolingually with speech only. This conflict constitutes an ethical problem for parents responsible for choosing between one of the two alternatives. This article puts forth the precautionary principle as a possible solution to this problem. Although scientific uncertainty exists in the case of (...) both doctrines, there exists a scenario of possible irreversible harm to some of the children habilitated monolingually. An application of the precautionary principle may hence suggest that it is rational to agree on the bilingual approach, at least for the time-being. (shrink)

This open access book presents an ethical approach to utilizing personal medical data. It features essays that combine academic argument with practical application of ethical principles. The contributors are experts in ethics and law. They address the challenges in the re-use of medical data of the deceased on a voluntary basis. This pioneering study looks at the many factors involved when individuals and organizations wish to share information for research, policy-making, and humanitarian purposes. Today, it is easy to donate blood (...) or even organs, but it is virtually impossible to donate one’s own medical data. This is seen as ethically unacceptable. Yet, data donation can greatly benefit the welfare of our societies. This collection provides timely interdisciplinary research on biomedical big data. Topics include the ethics of data donation, the legal and regulatory challenges, and the current and future collaborations. Readers will learn about the ethical and regulatory challenges associated with medical data donations. They will also better understand the special nature of using deceased data for research purposes with regard to ethical principles of autonomy, beneficence, and justice. In addition, the contributors identify the key governance issues of such a scheme. The essays also look at what we can learn in terms of best practice from existing medical data schemes. (shrink)

Trust is one of the big buzzwords in debates about the shaping of society, democracy, and emerging technologies. For example, one prominent idea put forward by the High‐Level Expert Group on Artificial Intelligence appointed by the European Commission is that artificial intelligence should be trustworthy. In this essay, we explore the notion of trust and argue that both proponents and critics of trustworthy AI have flawed pictures of the nature of trust. We develop an approach to understanding trust in AI (...) that does not conceive of trust merely as an accelerator for societal acceptance of AI technologies. Instead, we argue, trust is granted through leaps of faith. For this reason, trust remains precarious, fragile, and resistant to promotion through formulaic approaches. We also highlight the significance of distrust in societal deliberation, as it is relevant to trust in various and intricate ways. Among the fruitful aspects of distrust is that it enables individuals to forgo technology if desired, to constrain its power, and to exercise meaningful human control. (shrink)

Research on sustainability assurance is still in its beginnings. One of the key questions in this field that also is of the highest practical relevance is concerned with the quality of the assurance process. However, a common understanding of assurance quality and how it should be measured is still missing. We try to close this gap by building on the financial audit literature. We introduce a definition of assurance quality that comprises two key aspects: the depth of the assurance process (...) and the breadth of the assurance statement. Based on prior research, we hypothesize that a firm’s sustainability performance is related to the depth of the assurance process, while the type of the assurance provider, more precisely the affiliation to the accounting profession, is related to the breadth of the assurance statement. Results for a sample of 122 European firms reveal a negative relationship between sustainability performance and assurance process depth as well as between the affiliation to the accounting profession and assurance statement breadth. Thus, we find evidence that poor sustainability performers ask for in-depth assurance services, most likely as a means to enhance their internal sustainability-related processes and systems. Assurance providers that do not belong to the accounting profession in turn are associated with broader assurance statements. (shrink)

This text presents an overview of the bioethical debate on pediatric cochlear implants and pays particular attention to the analysis of the Deaf critique of implantation. It dismisses the idea that Deaf concerns are primarily about the upholding of Deaf culture and sign language. Instead it is argued that Deaf skepticism about child rehabilitation after cochlear surgery is well founded. Many Deaf people have lived experiences as subjects undergoing rehabilitation. It is not the cochlear technology in itself they view as (...) problematic, but rather the subsequent rehabilitation process. Because they themselves have experienced what they describe as harmful effects which relate above all to the idea of normalization, they have articulated worries for the new generations of deaf children in need of rehabilitation following cochlear implant surgery. These insights have attracted little attention, but could represent relevant ethical questions of which both practitioners and researchers in the field of implantation might be aware. (shrink)

In _"Masterpiece" Studies_ Kermit Champa offers new ways to interpret modernism that have previously been closed off by the application of the reigning art-historical methodologies to the study of the modernist achievement. He focuses on four separate phenomena—Manet's last Salon painting, _Bar at the Folies-Bergèr_e;_ L'Oeuvre_, Zola's novel about the realist/impressionist movement; Van Gogh's problematic versions of a single painting, _La Berceuse_; and the immanent "series" phenomenon of Monet's work of the period. Champa reveals the importance of music, in (...) particular Wagner's music, as a paradigm for later nineteenth-century French painting. He also shows the crucial significance of the concept of the masterpiece as thematized by Zola in his novel for our understanding of certain aspects of the art of Manet, Monet, and Van Gogh. Employing postformalist methodology, the book explores the conversation between works of art produced in close succession and elaborates an aesthetic context for that conversation. Champa also shows how paintings and fictional representations of paintings can announce their points in common, and it is out of this exploration that he radically redefines what constitutes "context.". (shrink)

In view of the numerous accounting and corporate scandals associated with various forms of moral misconduct and the recent financial crisis, economics and business programs are often accused of actively contributing to the amoral decision making of their graduates. It is argued that theories and ideas taught at universities engender moral misbehavior among some managers, as these theories mainly focus on the primacy of profit-maximization and typically neglect the ethical and moral dimensions of decision making. To investigate this criticism, two (...) overlapping effects must be disentangled: the self-selection effect and the treatment effect. Drawing on the concept of moral judgment competence, we empirically examine this question with a sample of 1773 bachelor’s and 501 master’s students. Our results reveal that there is neither a self-selection nor a treatment effect for economics and business studies. Moreover, our results indicate that—regardless of the course of studies—university education in general does not seem to foster students’ moral development. (shrink)

This paper argues that data-driven medicine gives rise to a particular normative challenge. Against the backdrop of a distinction between the good and the right, harnessing personal health data towards the development and refinement of data-driven medicine is to be welcomed from the perspective of the good. Enacting solidarity drives progress in research and clinical practice. At the same time, such acts of sharing could—especially considering current developments in big data and artificial intelligence—compromise the right by leading to injustices and (...) affecting concrete modes of individual self-determination. In order to address this potential tension, two key elements for ethical reflection on data-driven medicine are proposed: the controllability of information flows, including technical infrastructures that are conducive towards controllability, and a paradigm shift towards output-orientation in governance and policy. (shrink)

Ramscar and colleagues (2010, this volume) describe the “feature-label-order” (FLO) effect on category learning and characterize it as a constraint on symbolic learning. I argue that FLO is neither a constraint on symbolic learning in the sense of “learning elements of a symbol system” (instead, it is an effect on nonsymbolic, association learning) nor is it, more than any other constraint on category learning, a constraint on symbolic learning in the sense of “solving the symbol grounding problem.”.

ABSTRACT Although Kairos in Greek mythology is often depicted as the winged son of Zeus who grants to those who lay hold of his single lock of hair their once-in-a-lifetime opportunity, in traditional African American culture, particularly when it comes to speech, Kairos is essentially family. Given how much African American speakers depend on seizing the moment to invoke spiritual connections, emit laughter, and profess the truth, Kairos, or what we might call CPT (“Colored People’s Time”), can be summoned almost (...) at will. One of the African American discourses this article will use to illustrate this point is Call and Response, a verbal exchange in which speakers and listeners attune to one another and to the timeliness of an event. Martin Luther King Jr.’s “I Have a Dream” speech was such an event, but it wouldn’t have been so were it not for the timely responding of his favorite gospel singer, Mahalia Jackson. (shrink)

The neuregulin gene encodes a series of polypeptide growth factors that can influence the growth state of target vertebrate cells in culture. Recently, three studies have explored the in vivo function of the neuregulin signaling system in mice by disrupting the genes encoding the neuregulin ligand(1) and two of its receptors, ErbB2(2) and ErbB4(3). Each of the genes is essential for development, and aberrations in cardiac and neural development are particularly prominent in mutant embryos. The observed defects, together with the (...) localization of expression of the neuregulin signaling components within these tissues, highlight a paracrine mechanism for neuregulin‐mediated intercellular communication. (shrink)

People are habitual explanation generators. At its most mundane, our propensity to explain allows us to infer that we should not drink milk that smells sour; at the other extreme, it allows us to establish facts (e.g., theorems in mathematical logic) whose truth was not even known prior to the existence of the explanation (proof). What do the cognitive operations underlying the inference that the milk is sour have in common with the proof that, say, the square root of two (...) is irrational? Our ability to generate explanations bears striking similarities to our ability to make analogies. Both reflect a capacity to generate inferences and generalizations that go beyond the featural similarities between a novel problem and familiar problems in terms of which the novel problem may be understood. However, a notable difference between analogy-making and explanation-generation is that the former is a process in which a single source situation is used to reason about a single target, whereas the latter often requires the reasoner to integrate multiple sources of knowledge. This seemingly small difference poses a challenge to the task of marshaling our understanding of analogical reasoning to understanding explanation. We describe a model of explanation, derived from a model of analogy, adapted to permit systematic violations of this one-to-one mapping constraint. Simulation results demonstrate that the resulting model can generate explanations for novel explananda and that, like the explanations generated by human reasoners, these explanations vary in their coherence. (shrink)

A new era has emerged in research on entheogens largely due to clinical trials conducted at Johns Hopkins University and similar studies sponsored by the Council for Spiritual Practices. In these notes and queries, I reflect on implications of these developments for psychological studies of religion and on what this research may mean for Christian churches in the United States. I conclude that the aims and methods of this research fit well within Jamesian efforts of contemporary psychology of religion to (...) assess religious practices by their fruits for life. Furthermore, some communitarian religious concerns that religious experiences occasioned by entheogens pose risks to the integrity of religious community are shown to be largely unfounded. However, it is suggested that certain risks for religious life posed by all investigations/interventions by knowledge experts—in particular, the colonization of the religious life world and the commodification of its practices—also attend these developments for Christian churches. Additionally, risks of individual harm in the use of entheogens appear to be significant and, therefore, warrant earnest ethical study. (shrink)

The practical superiority of markets over governments has become readily apparent. Only the most dogmatic of state apologists continue to deny this obvious fact—at least with respect to the production of many goods and services. Free-market economists and libertarians go much further, of course. They affirm the market’s superiority in nearly all realms. Yet only a handful of anarchocapitalists, most notably Murray Rothbard, have dared claim that a free market could also do a better job of providing protection from foreign (...) states.1 National defense is generally considered the most essential of all government services. This widely conceded exception to the efficacy of markets seems to have irrefutable empirical confirmation. If private defense is better than government defense, why has government kept winning over the centuries? Indeed, the state’s military prowess has more than seemingly precluded the modern emergence of any anarchocapitalist society. At one time, as far as we know, all humankind lived in stateless bands of hunter-gatherers and had done so since the emergence of modern man some fifty thousand years ago. But beginning around 11,000 B.C., a gradual transition to.. (shrink)

Business and love appear to have little to do with each other. We hold the opposite to be true if the concept of love in business draws from two corresponding grammars. This paper contributes to the ‘agenda for growth and affirmation of people and the environment’ in business. By focusing on the grammars of love and business we operationalize the concept of love in ways that business executives, managers and employees can understand, adopt, and implement. With references to the theory (...) and practice of management and organizations, we aim to contribute to expanding the theory and practice of responsible organizations and their leaders caring for others. (shrink)

MUC1 and MUC4 are the two membrane mucins that have been best characterized. Although they have superficially similar structures and have both been shown to provide steric protection of epithelial surfaces, recent studies have also implicated them in cellular signaling. They act by substantially different mechanisms, MUC4 as a receptor ligand and MUC1 as a docking protein for signaling molecules. MUC4 is a novel intramembrane ligand for the receptor tyrosine kinase ErbB2/HER2/Neu, triggering a specific phosphorylation of the ErbB2 in the (...) absence of other ErbB ligands and potentiating phosphorylation and signaling through the ErbB2/ErbB3 heterodimeric receptor complex formed in the presence of neuregulin. In contrast, MUC1 has a highly conserved cytoplasmic tail, which binds β‐catenin, a key component of adherens junctions and a regulator of transcription, in a process that is tightly regulated by MUC1 phosphorylation. The specific localization of these membrane mucins to the apical surfaces of epithelial cells suggests that their signaling functions may be important as sensor mechanisms in response to invasion or damage of epithelia. BioEssays 25:66–71, 2003. © 2002 Wiley Periodicals, Inc. (shrink)

O‐glycosylation is the post‐translational process whereby carbohydrate is added to hydroxylated amino acids of proteins. The major O‐glycosylation pathway in animal cells is involved in the synthesis of oligosaccharides linked by N‐acetylgalactosamine to serine or threonine residues in ‘mucin‐type’ proteins or their analogs. In this review, we discuss the evidence for the cellular localization of the biosynthetic steps in this pathway and propose a simplified, consensus version. We also propose variations of the simple pathway to account for its heterogeneity and (...) variability in different cell types and differentiation states. (shrink)

Microfilament interactions with the plasma membranes of animal cells appear to vary with cell type and localization. In the erythrocyte, actin oligomers are associated with the membrane via spectrin and ankyrin. The ends of stress fibers in cultured cells, such as fibroblasts, are attached to the plasma membrane at focal adhesion sites and may involve the protein vinculin as a linking protein. In intestinal brush border microvilli a 110,000 dalton protein links the microfilament bundles to sites on the microvillus. A (...) transmembrane complex containing actin stably associated with a cell surface glycoprotein can be isolated from ascites tumor cell microvilli and can be obtained still associated with microfilaments by gentle extraction and gradient centrifugation of the microvilli. These varied interaction mechanisms are believed to be needed to satisfy the different structural and dynamic requirements of the particular systems. (shrink)