EIF2AK3 and cancer: An analysis of the three branches of the UPR by PCR and Western blotting in human cancer cells treated with Rv showed that aneuploidy triggers a global UPR including the upregulation of GRP78, and an overall activation of both PERK and IRE1α branches, with phosphorylation of eIF2α downstream of PERK being the hallmark of PERK involvement.