NQO1 is a cytosolic flavin-containing quinone reductase that catalyzes two-electron reduction of quinones to hydroquinones using NADH or NADPH as electron donors, thereby preventing the formation of toxic semiquinones and reactive oxygen species 1. The enzyme serves multiple cellular protective roles: it detoxifies endogenous substrates including ubiquinone and vitamin E quinone components of the plasma membrane redox system, acts as a superoxide reductase, and stabilizes tumor suppressors TP53 and TP73 against proteasomal degradation 1. NQO1 expression is markedly upregulated in solid tumors (up to 200-fold) through Nrf2-dependent mechanisms, making it a selective cancer biomarker 2. In pathological contexts, NQO1 dysregulation contributes to diabetes progression; NQO1 genetic variants (rs1800566 C609T) show decreased expression associated with Type 2 diabetes susceptibility 3. Conversely, NQO1 overexpression protects against diabetic nephropathy by suppressing TLR4/NF-κB and TGF-β/Smad inflammatory pathways 4. NQO1 also promotes breast cancer lung metastasis through stabilization of chaperone PPIA, triggering neutrophil extracellular trap formation 5. The enzyme's high tumor expression enables both therapeutic strategies—NQO1-activated prodrugs inducing ferroptosis in drug-resistant cancers 6—and diagnostic applications as a tumor-selective imaging target 2.