KEAP1 and cancer: In the absence of exogenous antioxidants, cancer cells maintain redox homeostasis by expressing endogenous antioxidants, many of which are regulated by the redox-sensitive transcription factor nuclear factor (erythroid-derived 2)-like 2 (NFE2L2, NRF2) and its negative regulator Kelch-like ECH-associated protein 1 (KEAP1) [14, 24, 25].