Quercetin regulates apoptosis and COX and nitric oxide (NO) synthase activities in the ethanol-induced ulcer model in rats, and it also increases the antioxidant enzyme activities, nuclear translocation of the nuclear factor related to erythroid 2 (Nrf2), and prevents the factor kappa B (NF-κB) activation. The gene discussed is NFKB1; the disease is ulcer disease.