A transfected H-ras oncogene does not inhibit differentiation of cardiac and skeletal muscle from embryonal carcinoma cells.

P19 embryonal carcinoma (EC) cells can be induced to differentiate in vitro into a variety of cell types, including cardiac and skeletal myocytes. We have isolated P19 cells stably transformed with either the activated human H-ras oncogene or with a chimeric gene in which the H-ras oncogene was controlled by a muscle-specific promoter. These P19 lines exhibited ubiquitous and muscle-specific expression of the activated H-ras protein, respectively. In both lines of P19 cells, normal cardiac and skeletal muscle differentiation was observed. Since the activated H-ras prevents differentiation of myoblast cell lines, our results suggest that the EC-derived muscle progenitor cell differs from continuous myoblast cell lines, perhaps by lacking a complementing oncogene responsible for myoblast immortalization.