In sharp contrast, the levels of phosphorylation of both PERK at Thr980 and eIF2α at Ser51 were increased by 2-fold in the cortex of the 12-months old 3xTg-AD mice (Figure 6B), whereas the protein levels of other components of the UPR analyzed such as BIP, PDI, IRE1α or CHOP remained unchanged between genotypes. This evidence concerns the gene ERN1 and Alzheimer disease.