PTEN and prostate cancer: Cross-comparison with human cancer data sets supported the relevance of these genes for PTEN-cooperating human prostate tumor suppression as they are significantly enriched in (1) known and putative human cancer genes, (2) genes whose mRNA expression levels decline concomitantly with those of PTEN in human prostate cancer samples, and (3) genes frequently inactivated by homozygous deletion in human prostate cancer.6