This gene encodes a secreted ligand of the TGF-beta (transforming growth factor-beta) superfamily of proteins. Ligands of this family bind various TGF-beta receptors leading to recruitment and activation of SMAD family transcription factors that regulate gene expression. The encoded preproprotein is proteolytically processed to generate each subunit of the disulfide-linked homodimer, which plays a role in bone and cartilage development. While a homozygous knockout mouse for this gene exhibits embryonic lethality, conditional knockout mice have defects in bone, cartilage and heart development. [provided by RefSeq, Jul 2016]