Levels of phosphorylated‐eIF2α, XBP1, and ATF‐6 (measures of ER stress) in total fractions were measured by immunoblotting in hSOD1‐WT‐ and hSOD1‐G93A‐expressing NSC‐34 differentiated cells, cultured as above, in the presence or absence of P110 (1 μM/24 h); β‐actin was used as a loading controls. Protein levels were quantified and presented as fold change of hSOD‐1 WT.