Platelet-derived growth factor: roles in normal and v-sis transformed cells.

Platelet-derived growth factor (PDGF) is the most potent mitogenic protein in human serum. The normal roles of this protein may relate to its potent mitogenic properties and its activities in directed cell migration and at sites of wounds. PDGF is a heterodimeric protein of approximately 30,000 molecular weight; one polypeptide chain of PDGF is highly homologous to the predicted amino acid sequence of p28v-sis, the putative transforming protein of simian sarcoma virus (SSV), suggesting a major role of growth factor activity in transformation by SSV. PDGF-like growth promoting activity is found in SSV-transformed cells and is secreted into conditioned media where it appears to interact with PDGF cell surface receptors to stimulate 3H-thymidine incorporation into DNA of cells secreting this protein. Transformation by SSV may in part be mediated by the autocrine stimulation of cell growth by the PDGF-like mitogenic properties of the transforming protein of SSV.