GPX3 and cancer: As the main scavenger of ROS, glutathione peroxidase 3 (GPX3) is considered to be a potent tumor suppressor in many cancers; nevertheless, GPX3 promoter hypermethylation could stop its antioxidant function in clear cell renal cell carcinoma (ccRCC), which indicates that the failure of the antioxidant system in ccRCC cells may be related to renal carcinogenesis [35].