DDIT3 and Alzheimer disease: 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.