Platelet derived growth factor (PDGF-A) is a potent mitogen for cells of mesenchymal origin. Binding of this growth factor to its affinity receptor elicits a variety of cellular responses. It is released by platelets upon wounding and plays an important role in stimulating adjacent cells to grow and thereby heal the wound. Its protein structure consists of antiparallel disulfide -linked dimer of nonidentical (A,B) chains. Homodimers of A and B chains are implicated in the transformation processes. A-A and B-Bovine, as well as A-B dimers can bind to the PDGF receptor. It belongs to the PDGF/VEGF growth factor family.