Secreted Frizzled Related Protein 1 (SFRP1)

Secreted frizzled-related protein 1 (SFRP1) is a member of the SFRP family that contains a cysteine-rich domain homologous to the putative Wnt-binding site of Frizzled proteins. SFRPs act as soluble modulators of Wnt signaling. SFRP1 and SFRP5 may be involved in determining the polarity of photoreceptor cells in the retina. SFRP1 is expressed in several human tissues, with the highest levels in heart.

SFRP1 is a 35 kDa prototypical member of the SFRP family. It acts as a biphasic modulator of Wnt signaling, counteracting Wnt-induced effects at high concentrations and promoting them at lower concentrations. It is located in a chromosomal region (8p12-p11.1) that is frequently deleted in breast cancer and is thought to harbour a tumor suppressor gene.