The secreted frizzled-related (sFRP) family of proteins represent the largest family of secreted inhibitors of Wnt. They inhibit the canonical, beta-catenin-dependent pathway and have been reported to also inhibit the non-canonical, planar cell polarity (PCP) signaling. They resemble the ligand-binding cysteine-rich domain (CRD) of frizzled (Fzd) receptors and interact with members of the Wnt family. An alternative model of Wnt inhibition is provided by the ability of sFRPs to interact with Fzd receptors and form non-functional complexes. For more details check PMID: 22653731 and references therein. The sFRPs members are listed with aliases in parentheses, full names and links to gene report pages:

Sfrp1 (FRP1, FRP-1, FrzA) – secreted frizzled-related protein 1
Sfrp2 (FRP-2, SDF-5, SARP1) – secreted frizzled-related protein 2
Frzb (sFRP-3, SFRP3) – frizzled-related protein
Sfrp4 (FRPHE) – secreted frizzled-related protein 4
Sfrp5 (SARP3) – secreted frizzled-related protein 5