DDIT3 and amyotrophic lateral sclerosis: Exposure of ALS NPCs to the ER stressor tunicamycin increased the ER stress markers binding immunoglobulin protein (BiP) and C/EBP homologous protein (CHOP), disrupted mitochondrial membrane potential, upregulated expression of the mitochondrial apoptotic marker, <i>BAX</i>, increased caspase-3 activation, and reduced cell viability.