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Platelet-derived growth factor: a multifunctional regulator of normal and abnormal cell growth.

Polypeptide growth factors, which are synthesized and secreted both by normal and transformed cells, have a multiplicity of roles in normal and abnormal cell growth. Platelet-derived growth factor (PDGF) is nearly identical to the transforming gene (oncogene) product of simian sarcoma virus p28v-sis. Binding of PDGF to high-affinity cell surface PDGF receptors stimulates the intrinsic autophosphorylating protein tyrosine kinase activity of these receptors and sets off a cascade of metabolic events. Among these events are induction of otherwise quiescent genes which regulate synthesis of transcriptional factors and thus are critical in cell division, differentiation and development.