Contrary to these benefits, and although low levels of Nrf2 activity predispose cells to chemical carcinogenesis, loss of Keap1 function and elevated Nrf2 levels have been detected in various cancer tumours, which enhances cell proliferation and resistance to chemotherapeutic drugs [[68], [69], [70]], a phenomenon dubbed the “dark side of Nrf2” [71] and the “double-edge sword of Nrf2” [72]. This evidence concerns the gene NFE2L2 and cancer.