PXR contributes to the chemotherapy outcome by interfering with the metabolism, drug resistance, tumor sensitivity, apoptosis and pharmacokinetics parameters of many chemotherapeutic agents, such as tamoxifen, irinotecan, vinblastine, doxorubicin, paclitaxel, cisplatin and ixabepilone in cancer cell lines and patients [11,14]. The gene discussed is NR1I2; the disease is cancer.