IL13 and asthma: Tauroursodeoxycholic acid effectively inhibits apoptosis partly by modulating the PRKR-like ER kinase-eukaryotic translation initiation factor 2 alpha ER stress pathway and the AKT pathway,45, 46 and reduces HDM-mediated asthma by inhibiting ER stress47 The ER stress blocker 4-phenylbutyric acid can reduce the expression of nuclear factor-kappaB, resulting in downregulation of the expression of Th2 cytokines (IL-4, IL-5, IL-13) and airway inflammatory response factors (IL-1β, tumor necrosis factor-alpha, interferon-gamma).48