The TGF-beta superfamily is composed of numerous growth differentiation factors, including transforming growth factor beta 1, 2 , and 3 (TGF-beta 1, TGF-beta 2 and, TGF-beta 3). TGF-beta 1 controls proliferation, differentiation and other functions in many cell types. TGF-beta 1 is a potent stimulator of osteoblastic bone formation, causing chemotaxis, proliferation and differentiation in committed osteoblasts. The inactive form consists of a TGF-beta 1 homodimer non-covalently linked to a latency-associated peptide (LAP) homodimer. The active form is a disulfide-linked homodimer of mature TGF-beta 1. Defects in TGF-beta 1 are the cause of Camurati-Emgelmann disease, a progressive diaphyseal dysplasia characterized by hyperostosis ans sclerosis of the diaphyses of long bones.