SOD2 and Alzheimer disease: Further, the phenotypic manifestation seen in AD model flies was correlated with increased mitochondrial/cellular ROS (Fig. 5I–L,Q–T,a) and an increased expression of anti-oxidant enzymes (Mn-SOD and CAT) in AD as a result of the compensatory mechanism against the increased ROS level (Fig. 5c) (Flynn and Melov, 2013; Niedzielska et al., 2016).