Soluble frizzled-related proteins (sFRPS) function as modulators of Wnt signaling through direct interaction with Wnts. They have a role in regulating cell growth and differentiation in specific cell types (By similarity). SFRP4 plays a role in bone morphogenesis. May also act as a regulator of adult uterine morphology and function. May also increase apoptosis during ovulation possibly through modulation of FZ1/FZ4/WNT4 signaling (By similarity). Has phosphaturic effects by specifically inhibiting sodium-dependent phosphate uptake (PubMed:12952927). Cytoplasmic in ovarian tumor cells. Expressed in mesenchymal cells. Highly expressed in the stroma of proliferative endometrium. Expressed in cardiomyocytes. Shows moderate to strong expression in ovarian tumors with expression increasing as the tumor stage increases. In ovarian tumors, expression levels are inversely correlated with expression of CTNNB1 (at protein level). Increased levels in failing myocardium. Up-regulated in several tumor types including ostomalacia-associated tumors and endometrial and breast carcinomas. The FZ domain is involved in binding with Wnt ligands. The disease is caused by variants affecting the gene represented in this entry. Belongs to the secreted frizzled-related protein (sFRP) family.