NFE2L2 and cancer: Though NRF2 up-regulation is widely considered to be beneficial in normal cells and acts as a blocking agent in the process of carcinogenesis, continuous activation of NRF2 within cancer cells, often caused by mutations in NRF2 or its major regulator Kelch-like ECH-associated protein 1 (KEAP1), leads to tumorigenesis, proliferation and drug resistance.