IGFBP4 and prostate cancer: This is consistent with its biologic function as an inhibitor of IGF activity.[27] While previous studies investigating the overexpression of IGFBP-4 in both colorectal and prostate cancers in vivo found evidence of decreased tumor proliferation, these correlations have not yet been performed in melanoma.[25,28] In this regard, our group has found evidence to suggest that integrin αvβ3 can mediate the expression of IGFBP-4 Specifically, treatment of M21 melanoma cells with a monoclonal antibody directed against αvβ3 results in an elevation of IGFBP-4 levels both in vitro and in vivo.