BMP-6 (Bone Morphogenetic Protein 6) forms disulfide-linked homodimers and heterodimers with BMP-2 that signal through complexes of type I (Activin RIA/ALK-2 and BMPR-IA/ALK-3) and type II (Activin RIIA and BMPR-II) receptors. BMP-6 promotes osteoblast differentiation from mesenchymal stem cells, chondrocyte maturation, Ang II-induced aldosterone production in the adrenal cortex, and hormone production and responsiveness in ovarian granulosa cells. It promotes neurite outgrowth, neuroprotection, angiogenesis, immune tolerance, and tumor progression. BMP-6 binds to RGM-C/Hemojuvelin to enhance Hepcidin expression and prevent serum iron overload. Heterodimers of BMP-2 and BMP-6 show increased potency at inducing bone formation compared to either BMP-2 or BMP-6 homodimers.