The moderate and highly significant positive correlation between Mcl-1 and USP9x immunoreactivity (Spearman’s r = 0.560, p = 0.000043; Pearson’s r = 0.510, p = 0.00025) proposed an interrelation between the anti-apoptotic protein Mcl-1 and the deubiquitylating enzyme USP9x in prostate cancer. This evidence concerns the gene USP9X and Familial prostate cancer.