NQO1 and cancer: NQO1 has been shown to play a role in the activation of cancer chemotherapeutic agents,1,20,28 detoxification of xenobiotics29 and cancer prevention.20,28 Activation of bioreductive agents by NQO1 has been extensively studied.1,20 Cells with elevated NQO1 levels are more sensitive to MMC and drug activity is decreased by the NQO1 inhibitor, dicoumarol.30–32 Thus, NQO1 is a major activating enzyme for MMC.