In support of this, phosphorylated PKR and its PACT activator have been shown to colocalize in brains from Alzheimer???s disease (AD) [52]. 3.4. eIF2?? Phosphorylation and AutophagyIn response to a stress such as nutrient deprivation or viral infection, cells make use of their eIF2?? kinases to inhibit the translation of unnecessary or unwanted protein synthesis.