SOD1 and amyotrophic lateral sclerosis: Another key function of mitochondria concerns the regulation of cytosolic calcium levels: several studies reported a loss of Ca2+ binding proteins in motoneurons of ALS patients related to the presence of mutant SOD1 (Bernard-Marissal et al., 2012; Mattson, 2013), which leads to reduced calcium uptake from the cytoplasm, increasing the sensitivity to excitotoxicity.