H2AX and amyotrophic lateral sclerosis: After characterizing our cell culture model, experiments on human SOD1 mutant iPSC-derived motor neurons revealed that DDR was activatable in diseased motor neurons, as evidenced by the accumulation of phosphorylated H2A.X, and that DNA repair capacity and kinetics in ALS motor neurons were similar to wildtype motor neurons, as reported by the disappearance of phosphorylated H2A.X.