The invention provides a novel, secreted protein that contains a region homologous to ligand binding domain of a cytokine receptor. This protein, called Frizzled-related protein (FRP), antagonizes the signaling of the Wnt family of cytokines. Extracellular signaling molecules such as the Wnt family members have essential roles as inducers of cellular proliferation, migration, differentiation, and tissue morphogenesis. As Wnt molecules are known to participate in the aberrant growth associated with neoplasia, Wnt antagonists such as FRP are valuable tools which both for understanding oncogenesis and for the design of new cancer therapies.