However, it is important to note the negative aspects of NRF2, with special emphasis on its effects on cancer cells.(124,125) In experimental mice, mutation of the gene encoding NRF2 or overexpression of NRF2 by KEAP1 knockout enhances cancer cell proliferation.(126,127) Stimulation of ABC transporters and multidrug resistance protein 2 (MDR2) by NRF2 facilitates the clearance of anticancer drugs, which in turn induces chemoresistance in cancer cells and promotes tumor growth.(128,129) Such cases have been reported clinically for several types of cancers. The gene discussed is ABCG2; the disease is cancer.