CYR61 is a member of the CCN family of secreted cysteine rich regulatory proteins. CYR61 induces angiogenesis by stimulating the proliferation, migration, and adhesion of endothelial cells. Cell migration and adhesion are mediated through binding to specific cell surface integrins and to heparin sulfate proteoglycans. Increased expression of CYR61 is associated with several types of cancer, and correlates with the progression and estrogen independence of human breast cancers. Recombinant human CYR61 is a 39.4 kDa protein containing 357 amino acid residues. It is composed of four distinct structural domains (modules); the IGF binding protein (IGFBP) domain, the von Willebrand Factor C (VWFC) domain, the Thrombospondin type-I (TSP type-1) dom