HMOX1 and neoplasm: When exposed to oxidative or electrophilic stress, Nrf2 combines with antioxidant response elements (ARE) within the promoter region of target genes and activates related antioxidant molecules, such as NADPH, heme oxygenase-1 (HO1), Nrf2-driven antioxidant molecules NAD(P)H: quinine oxidoreductase-1 (NQO1), etc., thereby defending cancer cells against oxidative damage and enhancing tumor radioresistance [31].