Abstract

How cell commitment and differentiation are controlled in the early stages of embryogenesis is a problem that has long fascinated developmental biologists. Retinoic acidinduced differentiation of embryonal carcinoma cells in culture provides a model in which these questions can be explored. Recent work has yielded exciting insights into the central series of molecular changes which drives the commitment of these cells to formation of a new phenotype. Interacting with the key molecules in this central pathway is a variety of transcription factors, many of which show changes in availability and/or activity during differentiation. In various combinations, these modulate the activities of genes involved in both cell proliferation and in the production of extracellular matrix and other proteins characteristic of differentiated cells.