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Growth differentiation factor 6 （GDF-6）, also known as bone morphogenetic protein 13 （BMP-13）, is a member of the transforming growth factor-beta （TGF-β） superfamily of cytokines that plays a critical role in skeletal development and joint maintenance. In humans, GDF-6 is expressed in various tissues, including cartilage, bone, and synovium, and is involved in regulating chondrogenesis, osteogenesis, and joint homeostasis. GDF-6 exerts its biological effects by binding to specific cell surface receptors, such as the BMP receptors, leading to the activation of downstream signaling pathways, including Smad and non-Smad pathways. Through its signaling activities, GDF-6 promotes the differentiation of mesenchymal stem cells into chondrocytes and osteoblasts, as well as the maintenance of cartilage integrity and joint function. GDF-6 is considered a key regulator of skeletal development and joint health, with implications for musculoskeletal disorders and regenerative medicine.