SOD2 and neoplasm: For example: 1) MnSOD heterozygous KO mice had an increased incidence of tumors, however, these mice had a similar lifespan compared to WT mice [40]; 2) single housed calorie restricted (CR) male C57BL/6 mice had less fatal tumors, but the lifespan was similar to multiple housed CR mice [29]; and 3) CR with exercise reduced the fatal tumor incidence in F344 rats, but the maximum lifespan was similar to sedentary CR rats [41].