A significant increase in PDI expression, alongside other ER stress markers such as ERp57, was reported in ALS spinal cord and CSF compared to controls and also in the G93A SOD1 mouse model of ALS (Atkin et al., 2006, 2008; Massignan et al., 2007; Honjo et al., 2011a). Here, SOD1 is linked to amyotrophic lateral sclerosis.