The avoidance of H2O2 overproduction is likely to be the cause of no promotion of cancer cells when there is simultaneous overexpression of SOD2 and CAT both in vitro [247] and in vivo [246] and of tumor-preventive [249] and tumor-suppressive [243] effects in the case of the simultaneous overexpression of SOD2 and GPX1. Here, CAT is linked to cancer.