Platelet-derived growth factor-BB (PDGF-BB) is one of the five dimeric proteins belonging to the PDGF family. Other members are homodimers PDGF-AA, PDGF-CC, PDGF-DD, and the heterodimer PDGF-AB. 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-BB plays a role in angiogenesis and smooth muscle formation during embryonic development, as well as wound healing and regeneration in adults. Two receptors have been identified for the PDGF proteins – PDGFR alpha and PDGFR beta. PDGF-BB binds to PDGFR alpha, as well as PDGFR beta which appears to be specific for PDGF-BB and PDGF-AB.