Abstract

Mouse embryo cells, primed to differentiate with the hypomethylating agent 5‐azacytidine (5‐aza‐CR), provide an excellent model system in which cellular differentiation can be studied at the molecular level. An inherent advantage of this system is the availability of clonal populations of cells representative of the non‐differentiated precursor, those whose determinative state is that of a specific lineage, and the end stage, phenotypically mature cell. Analysis of these cultures at the cellular and molecular level will advance our understanding of requirements for and the mechanism of action of growth modulators as well as the necessity for controlled expression of certain proto‐oncogenes. At a more fundamental level, the system can be used to identify, isolate and characterize genes whose expression alters the phenotypic fate of cells.