Platelet-derived growth factor-AB (PDGF-AB) is one of the five dimeric proteins belonging to the PDGF family. Other members are homodimers PDGF-AA, PDGF-BB, PDGF-CC and PDGF-DD. The PDGFs are produced by platelets, stored in platelet alpha-granules and are released upon platelet activation. PDGF proteins are generally considered as potent mitogens for connective tissue cells, and can also be chemotactic for fibroblasts, smooth muscle cells, neutrophils and mononuclear cells. PDGF-AB is reported to support angiogenesis in the heart. Two receptors have been identified for the PDGF proteins - PDGFR alpha and PDGFR beta. PDGF-AB is able to bind to both PDGFR alpha and PDGFR beta.