SFRP4, also known as secreted frizzled-related protein4, is a family of vertebrate proteins which contain homology to the ligand-binding domain of the Frizzled family of transmembrane receptors. It is expressed in brain, kidney, lung, ovary, prostate, mammary gland and endometrium. This protein act as soluble modulators of Wnt signaling, counteracting Wnt-induced effects at high concentrations and promoting them at lower concentrations. It is able to bind Wnt proteins and Frizzled receptors in the extracellular compartment. Recombinant human SFRP4, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.