Recently, studies have shown that the elevated expressionof VCAM-1 was involved in tumor cell adhesion on endothelium cellsrelated to metastasis.16,17 Like GPNMB, this overexpressionwas associated with poor prognosis in many cancers including breastcancer,18 melanoma,19 colorectal cancer,20 ovariancancer,21 and prostate cancer.22 Overall, the high expression of GPNMB and VCAM-1in cancers and their functional association with cancer cell growthand metastasis make them important targets for development of antitumortherapeutics. This evidence concerns the gene GPNMB and prostate cancer.