EIF2AK2 and infection: At different times post-infection, cell extracts were immunoprecipitated with antibodies directed against PKR or eIF2α, after which the degree of PKR or eIF2α phosphorylation was examined using anti-phospho PKR (residue Thr451) or anti-phospho eIF2α (residue Ser51) antibodies and by performing quantification of the p-PKR/PKR or the p-eIF2α/eIF2α ratio.