As shown by the results of immunohistochemistry staining (Figure 6A), the protein levels of SOD2 were down-regulated significantly by iohexol in the CI-AKI group, which were remarkably restored by XP (200 mg/kg) treatment with increased positive expression in the cytoplasm (p < 0.05, Figure 6B). The gene discussed is SOD2; the disease is acute kidney injury.