– Ligand for members of the frizzled family of seven transmembrane receptors. Acts in the canonical Wnt signaling pathway by promoting beta-catenin-dependent transcriptional activation. In some developmental processes, is also a ligand for the coreceptor RYK, thus triggering Wnt signaling. Plays an essential role in the development of the embryonic brain and central nervous system (CNS). Has a role in osteoblast function, bone development and bone homeostasis.