eIF2α is activated by additional kinases: RNA-like ER kinase (PERK) in response to endoplasmic reticulum stress, protein kinase R (PKR) in response to virus infection, and eIF2α kinase heme-regulated inhibitor (HRI) in response to heme deprivation (Fig. 4E) [37]. Here, EIF2AK2 is linked to viral infectious disease.