Specifically, carnosine markedly inhibited 6-OHDA-induced upregulation of the ISR-related genes, Chop, Gadd34, and Atf4. Cellular stress signals (such as ER stress and viral infection) activate protein kinase R-like ER kinase, RNA-activated protein kinase, heme-regulated inhibitor, and general control non-derepressible 2 that converge on phosphorylation of eukaryotic translation initiation factor 2α (eIF2α), the core of ISR. This evidence concerns the gene PPP1R15A and viral infectious disease.