The adenovirus-5 12S E1a protein, but not the 13S induces expression of the endoA differentiation marker in F9 cells.

F9 embryonal carcinoma (EC) cells serve as a model system for early mammalian development. We have investigated the effect of the E1a gene products on the F9 cell differentiation program by stably introducing into these cells plasmids which express wild type or mutant forms of E1a. We have found that expression of the 12S E1a mRNA product results in the expression of the endoA gene, a marker specific for the differentiated phenotype of F9 cells, as well as an altered cell morphology associated with the differentiated state. These alterations are not observed in F9 cells which express the 13S E1a product. Other markers specific for the differentiated state are regulated normally in the E1a transformants following exposure to retinoic acid (R.A.) and dibutyryl cyclic AMP (dbcAMP). We discuss these results in the context of the well established transcriptional activities of the E1a proteins.