The UPR refers to a group of signalling pathways that collectively respond to the accumulation of aberrantly folded proteins, or other stresses otherwise incurred by the ER. As these stresses are common in viral infections, the UPR is a central anti-viral response pathway. The purpose of the UPR is to restore ER homeostasis in the event of disruption to protein synthesis, secretion, or degradation. UPR dysregulation is a hallmark of multiple pathologies, including neurodegenerative and fibrotic diseases . ER stress is also a critical factor in the pathogenesis of many respiratory diseases .