Platelet-derived growth factor (PDGF-A and PDGF-B subunits) is a potent mitogen for cells of mesenchymal origin. Binding of PDGF to its receptor PDGFR triggers a variety of cellular responses. PDGF is released by platelets upon wounding and plays an important role in stimulating adjacent cells to grow and heal the wound. PDGF consists of antiparallel disulfide-linked dimer of non identical (A and B) chains. Homodimers of A and B chains are implicated in transformation processes. A-A and B-B homodimers as well as A-B heterodimers bind to the PDGF receptor. A chromosomal aberration involving PDGF-B is a cause of dermatofibrosarcoma protuberans (DFSP), an uncommon aggressive tumor of the deep dermis and subcutaneous tissue. PDGF-B is available under the name Regrane, Xenopus/Amphibian, (Ortho-McNeil) to promote healing in diabetic neuropathic foot ulcers.