Furthermore, AR and PSA protein expression in PCa is frequently discordant with some PCa cells completely lacking the expression of either or both [2, 3, 5] Using a lentiviral PSA reporter (i.e., PSAP-GFP), we were able to separate the PSA−/lo PCa cells from the PSA+ counterparts to study their distinct biological and tumorigenic properties. This evidence concerns the gene KLK3 and posterior cortical atrophy.