Parthenolide, a sesquiterpene lactone derived from the herbal medicine feverfew, has been reported to produce a selective radiosensitization in prostate cancer cells and not effect normal prostate epithelial cells by activation of NADPH oxidase, which is an important source of ROS in prostate cancer cells and by suppressing antioxidants agents. The gene discussed is FMO5; the disease is prostate carcinoma.