P4HB and amyotrophic lateral sclerosis: Interestingly, an increase in PDI expression, preceded by the activation of both IRE1/XBP1 and ATF6 pathways, has been reported to occur during active myelination in cortical regions of rats.46 In line with this, a strong PDI expression in oligodendrocytes was observed in SOD1 mice,47 which was characterized by abnormalities in plasma and membrane lipid signalling, especially in the early symptomatic stages of ALS.47 In spinal cord, specific PDIs including PDIA4 and DNAJC10 correlated with ENO2, whose expression was decreased.