Abstract

The mechanism(s) by which the thymidine analogue 5‐bromodeoxyuridine (BUdR) specifically inhibits the expression of differentiated functions is poorly understood, as are the ways in which cells regulate processes exhibiting probabilistic aspects. I have developed a theoretical model for the regulation of the decision of myogenic cells to differentiate that can explain both of the above phenomena. This model provided a strategy for isolating myoblast variants that had amplified the expression of the factors regulating the decision to differentiate. These myoblasts served as the source of mRNA for making and screening a cDNA library in order to isolate these factors. The successful cloning of these genes should represent a major advance in our understanding of the molecular basis for the major coordinated changes in gene expression that accompany cell differentiation.