ER stress has indeed been implicated in a number of neurodegenerative diseases [199]; In ALS, a longitudinal study of a commonly used mouse model—the superoxide dismutase 1 (SOD1) transgenic mouse—revealed that the more vulnerable MNs are those that exhibit a UPR before showing signs of degeneration, suggesting a causal link between ER stress and MN death [200]. Here, SOD1 is linked to neurodegenerative disease.