Three sensors of ER stress - activating transcription factor 6 (ATF6), inositol-requiring enzyme 1 (IRE1) and protein kinase RNA-like endoplasmic reticulum kinase/ eukaryotic translation initiation factor-2α kinase 3 (PERK) - initiate the UPR in cancer cells [3, 13]. The gene discussed is EIF2AK3; the disease is cancer.