BMPs (bone morphogenetic proteins) belong to the TGF-β superfamily of structurally related signaling proteins. These ligands mediate numerous physiological processes. BMPs initiate, promote and maintain cartilage and bone development, growth, remodeling and repair, in both prenatal development and postnatal growth of eye, heart, kidney, skin, and other tissues. Expression of BMP-13 has been found in the hypertrophic chondrocytes of ossifying long bone centers.