R-spondin-1 (Rspo1)

Upon binding to LGR4-6 (LGR4, LGR5 or LGR6), LGR4-6 associate with phosphorylated LRP6 and frizzled receptors which are activated by extracellular Wnt receptors, triggering the canonical Wnt signaling pathway to increase expression of target genes (PubMed:21693646). 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 modulate the TGF-beta pathway.