EIF2AK4 and viral infectious disease: In mammals, four elF2α kinases, i.e., General control nonderepressible 2 (GCN2), eukaryotic translation initiation factor 2-alpha kinase 3 (PERK), interferon-induced, double-stranded RNA-activated protein kinase (PKR), and eukaryotic translation initiation factor 2-alpha kinase 1 (HRI), phosphorylate elF2α in response to amino acid starvation (AAS), ER stress, viral infection, and heme deficiency, respectively [3] (Figure 1).