Another example is 1,4-bis-([2-(dimethylamino-N-oxide)ethyl]amino)5,8-dihydroxy anthracene-9,10-dione (AQ4N), a bioreductive drug that requires CYP2S1 and CYP2W1 activation in tumor tissues to be transformed into an inhibitor of topoisomerase II [118]. The gene discussed is CYP2W1; the disease is neoplasm.