TRANSFORMING GROWTH FACTOR-BETA-1-MEDIATED GROWTH-INHIBITION IN CHICK-EMBRYO FIBROBLASTS - REVERSION BY VIRALLY-EXPRESSED NUCLEAR ONCOGENES

Transforming growth factor beta1 (TGF-beta1) inhibits growth of primar y cultures of chick embryo fibroblasts by affecting G1 and strongly in creasing the generation time. This inhibition is reversed by the nucle ar oncogenes v-jun, v-fos, v-myc, but not v-erbA and v-ets. It is also reversed by v-myb from either avian myeloblastosis virus or avian E26 retrovirus. Taken together, these results strongly suggest that indep endent, functional interferences may take place between the TGF-beta1- induced growth inhibitory pathway and the oncogen-driven stimulatory p athway(s) at the level of the AP-1, Myc, and Myb transcription factors .