Platelet-derived growth factor is commonly known as a mitogen. Many research data suggest a role for PDGF-beta R in the mitogenic response of mesangial cells. There are four members of PDGF family known as PDGF-A chain, PDGF-B chain, PDGF-C chain and PDGF-D chain, which in active forms are dimers. As far as two receptors PDGF-alpha R and PDGF-beta R are known to bind PDGF.