Expression of PXR has been found in human prostate tumor tissues, and treatment of PC-3 cells with SR12813 (a selective agonist of PXR) stimulates the expression of multidrug resistance 1 (MDR1) and CYP3A4 and enhances the resistance of these prostate cancer cells to chemotherapy. This evidence concerns the gene CYP3A4 and Familial prostate cancer.