HMOX1 and esophagitis: RE control rats exhibited the down-regulation of antioxidant-related proteins, such as nuclear factor-erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expression levels, in the presence of esophagitis; however, the levels with Rhei Rhizoma treatment were significantly higher than those in RE control rats.