SOD2 and colorectal carcinoma: As one of the most important antioxidant enzymes, MnSOD protein has been considered downregulated in malignant neoplasms in the earliest studies, though subsequent researchers have found increased MnSOD expression in malignant mesothelioma and some neoplasms arising from thyroid, kidney and central nervous system cells as well as in CRC in most clinical studies [14].