Growth differentiation factor 5(GDF-5) is a member of the bone morphogenetic protein (BMP) family and the TGF-beta superfamily. This protein plays a role in chondrogenesis and chondrocyte metabolism, tendon and ligament tissue formation, and bone repair. It also increases the survival of neurones that respond to a neurotransmitter called dopamine, and is a potential therapeutic molecule associated with Parkinson's disease.