– Transforming Growth Factor β-1 (TGFβ-1) is a secreted protein which belongs to the TGF-β family. TGFβ-1 is abundantly expressed in bone, articular cartilage and chondrocytes and is increased in osteoarthritis (OA). TGFβ-1 performs many cellular functions, including the control of cell growth, cell proliferation, cell differentiation and apoptosis. The precursor is cleaved into a latency-associated peptide (LAP) and a mature TGFβ-1 peptide. TGFβ-1 may also form heterodimers with other TGFβ family members. It has been found that TGFβ-1 is frequently upregulated in tumor cells. Mutations in this gene results in Camurati-Engelmann disease.