a FAD-binding flavoprotein enzyme that that prevents the one electron reduction of quinones that results in the production of radical species. Involved in detoxification pathways as well as in biosynthetic processes such as the vitamin K-dependent gamma-carboxylation of glutamate residues in prothrombin synthesis. Mutations have been associated with tardive dyskinesia (TD), an increased risk of hematotoxicity after exposure to benzene, and susceptibility to various forms of cancer. The expression of NQO1 is increased in liver, colon and breast tumors and non-small cell lung cancer (NSCLC) compared with the normal tissues. Moreover, expression levels are also elevated in developing tumors, suggesting a role for NQ01 in the prevention of tumor development. A homozygous common missense variant (NQO1(*)2, rs1800566(T)), that disables NQO1 strongly predicts poor survival among two independent series of women with breast cancer. Studies on NQO1 knockout mice suggest that the lack of NQO1 enzymatic activity changes intracellular redox states resulting in a reduction in apoptosis, which in turn leads to myeloid hyperplasia of bone marrow. Altered expression is associated with Alzheimer's disease (AD). Inhibited by dicoumarol. 2 isoforms of the human protein are produced by alternative splicing. Note: This description may include information from UniProtKB.