Activator of the canonical Wnt signaling pathway by acting as a ligand for LGR4-6 receptors. Upon binding to LGR4-6 (LGR4; LGR5 or LGR6); LGR4-6 associate with phosphorylated LRP6 and frizzled receptors that are activated by extracellular Wnt receptors; triggering the canonical Wnt signaling pathway to increase expression of target genes. Also regulates the canonical Wnt/beta-catenin-dependent pathway and non-canonical Wnt signaling by acting as an inhibitor of ZNRF3; an important regulator of the Wnt signaling pathway. Acts as a ligand for frizzled FZD8 and LRP6. May negatively regulate the TGF-beta pathway. Has a essential roles in ovary determination. {ECO:0000269|PubMed:16109882; ECO:0000269|PubMed:21727895; ECO:0000269|PubMed:21909076; ECO:0000269|PubMed:22575959; ECO:0000269|PubMed:22615920; ECO:0000269|PubMed:22815884; ECO:0000269|PubMed:23756652; ECO:0000269|PubMed:23809763}.