SOD1 and nasopharyngeal carcinoma: However, SOD converts superoxide radical into hydrogen peroxide thus may establish an elevation of H2O2. Interestingly, subsequent analysis of the data demonstrated that MnSOD can promote protein expression level of catalase (Figure 4C, 4H) and H2O2 diminished (Figure 4D, 4I), which suggest that more MnSOD would be unlikely to yield more H2O2 in NPC cells.