Noggin binds to and antagonizes bone morphogenetic protein (BMP) ligands of the transforming growth factor beta (TGF-β) family. Noggin supports maintenance of undifferentiated human embryonic stem cells cultured in mouse embryonic fibroblast (MEF)-conditioned meduim (Chaturvedi et al.), and promotes dopaminergic differentiation of embryonic stem cells and subsequent survival of dopamine neurons (Chiba et al.). Noggin is essential for development of ectodermal structures including neural tube, tooth, hair follicle, and eye, as well as patterning of mesodermal somites and skeletal structures. It also influences chondrogenesis, osteogenesis, and joint formation (Krause et al.).