Activated fos oncogene in rat embryo fibroblasts transformed by ras and myc oncogenes

Rat embryo fibroblasts (REF) were transformed by simultaneous gene transfer of the complementary oncogenes ras and myc using the calcium phosphate coprecipitation method. Cell lines derived from transformation foci expressed in addition to ras and myc cellular oncogene fos while normal REF did not express ras, myc and fos according to the hybridization methods used. The transformed cell lines produced colonies in soft agar and tumors in newborn syngeneic rats. From one tumor a cell line was established which was characterized by a high level of fos gene expression.