ERN1 and infection: For example, hepatitis C virus (HCV) infection up-regulates the activating transcription factor 6 (ATF6) and inositol-requiring enzyme 1 (IRE1)–X-box binding protein 1 (XBP1) pathways [9], and enterovirus 71 (EV71) infection induces the protein kinase R-l like ER kinase (PERK)–eukaryotic initiation factor 2α (eIF2α) pathway.