In addition, when the therapeutics applied to malignant tumors account for the O2 → H2O2 process, chemical drugs, i.e. cisplatin and doxorubicin, have been found to activate superoxide dismutase (SOD)-mediated redox reaction to generate H2O2 from O2 in cancer cells.10,11 However, this process is restricted to the treatment of hypoxic tumors. Here, SOD1 is linked to cancer.