Ligand for members of the frizzled family of seven transmembrane receptors (Probable). Acts in the canonical Wnt signaling pathway by promoting beta-catenin-dependent transcriptional activation (PubMed:23499309, PubMed:26902720, PubMed:28528193, PubMed:23656646). In some developmental processes, is also a ligand for the coreceptor RYK, thus triggering Wnt signaling (By similarity). Plays an essential role in the development of the embryonic brain and central nervous system (CNS) (By similarity). Has a role in osteoblast function, bone development and bone homeostasis (PubMed:23499309, PubMed:23656646). Forms a soluble 1:1 complex with AFM; this prevents oligomerization and is required for prolonged biological activity (PubMed:26902720). The complex with AFM may represent the physiological form in body fluids (PubMed:26902720). Interacts with PORCN. Interacts with RSPO1, RSPO2 and RSPO3 (By similarity). Interacts with WLS (By similarity). Palmitoleoylation is required for efficient binding to frizzled receptors. Palmitoleoylation is necessary for proper trafficking to cell surface (Probable). Depalmitoleoylated by NOTUM, leading to inhibit Wnt signaling pathway (By similarity). Genetic variations in WNT1 define the bone mineral density quantitative trait locus 16 (BMND16) [MIM:615221]. Variance in bone mineral density influences bone mass, contributes to size determination in the general population, and is a susceptibility factor for osteoporotic fractures. Disease susceptibility is associated with variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the Wnt family. A palmitoylation site was proposed at Cys-93, but it was later shown that this cysteine is engaged in a disulfide bond.