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. SFRP1 decreases intracellular beta-catenin levels (By similarity). Has antiproliferative effects on vascular cells, in vitro and in vivo, and can induce, in vivo, an angiogenic response. In vascular cell cycle, delays the G1 phase and entry into the S phase. In kidney development, inhibits tubule formation and bud growth in metanephroi (By similarity). Inhibits WNT1/WNT4-mediated TCF-dependent transcription (By similarity). Interacts with WNT8, WNT1, WNT2, WNT4 and FRZD6 (By similarity). Interacts with MYOC. Cell membrane or extracellular matrix-associated. Released by heparin-binding (By similarity). Highly expressed in kidney and embryonic heart. Also highly expressed in the eye, where it is principally localized to the ciliary body and the lens epithelium. Weaker expression in heart, lung and brain. In the brain, is expressed exclusively in the choroid plexus. In the developing kidney expressed at 13.5 dpc in the periphery of the metanophros and surrounding the uretic and nephrogenic tubules. At 14.5 dpc, expression decreases in the outer cortical cells and becomes visible in the tubular parts of the nephron. From 15.5 dpc, highly expressed in the future loops of Henle. In the developing CNS, expression located to the forebrain and hindbrain. At 8.0 dpc, expressed in the future forebrain and in the ventral portion of the presumptive hindbrain. At 8.5 dpc, expression is maintained in these tissues with a strong signal in rhombomere 4. Until 11.5 dpc, expression continues in the hindbrain with additional expression at 9.5 dpc and 10.5 dpc, in the nasal and epibranchial placodes. In the forbrain, initial expression is found in the proencephalon of the forebrain, and then strong expression in the telencephalic vesicle up to 15.5 dpc. Expression is then found in specific cell populations throughout the brain. In the developing eye, expression, by 10.5 dpc, is confined to ectodermal cells overlying the dorsal part of the optic cup. In later stages, expression limited to the lens fiber cells and the future pigmented retina. By 15.5 dpc, expression is confined to the anterior part of the lens. During limb development, barely expressed until later stages, when it is found in the distal part of the separating phalanges. In other developing structures, expressed in nasal placodes at 9.5 dpc, in medial nasal processes at 10.5 dpc and then in the anterior portion of the invaginating olfactory epithelium. At 15.5 dpc, expressed on the basal side of the nasal epithelium. Also expressed in developing teeth, with the highest levels at 15.5 dpc and 16.5 dpc in the mesenchyme and the dental epithelium of the developing molars. As well, expressed in the ventral body wall, in the mesenchyme derived adrenal cortex, the cochlear epithelium and the branching epithelium of the salivary gland. In the developing heart, weakly expressed from 8.5 dpc in the tubular heart endocardium and myocardium. From 8.5 dpc to 12.5 dpc expressed in cardiomyocytes. At 9.5 dpc, expression found in the common ventricular and atrial chamber of the developing heart, in the aortic sac and in the sinus venosus. High expression found from 11.5 dpc-12.5 dpc, in the trabeculated wall of the ventricular chamber together with the wall of the atrial chamber. Expression also found in the muscular part of the interventricular septum. From 9.5 dpc-11.5 dpc expression in the visceral yolk sac confined to the inner lining endothelial cell layer. Expression in the developing heart decreases after 14.5 dpc. The FZ domain is involved in binding with Wnt ligands. Belongs to the secreted frizzled-related protein (sFRP) family.