Growth factor of the TGF-beta superfamily that plays essential roles in many developmental processes, including cardiogenesis, neurogenesis, and osteogenesis. Induces cartilage and bone formation. Initiates the canonical BMP signaling cascade by associating with type I receptor BMPR1A and type II receptor BMPR2. Once all three components are bound together in a complex at the cell surface, BMPR2 phosphorylates and activates BMPR1A. In turn, BMPR1A propagates signal by phosphorylating SMAD1/5/8 that travel to the nucleus and act as activators and repressors of transcription of target genes. Can also signal through non-canonical pathways such as ERK/MAP kinase signaling cascade that regulates osteoblast differentiation. Stimulates also the differentiation of myoblasts into osteoblasts via the EIF2AK3-EIF2A-ATF4 pathway by stimulating EIF2A phosphorylation which leads to increased expression of ATF4 which plays a central role in osteoblast differentiation. Homodimer; disulfide-linked. Interacts with SOSTDC1 (By similarity). Interacts with GREM2, RGMA, RGMB and RGMC. Interacts with ASPN (By similarity). Interacts with MAFP5 (By similarity). Interacts with FBN1 (via N-terminal domain) and FBN2. Interacts with type I receptor BMPR1A. Interacts with type II receptor BMPR2 (By similarity). Interacts with SCUBE3 (By similarity). Interacts with TNFAIP6 (primarily via Link domain); this interaction is inhibited by hyaluronan. Expressed in femur, calvaria, trachea, lung and ovary. Belongs to the TGF-beta family.