ERN1 and inflammatory bowel disease: Of note, the expression of IRE1α/IRE1β and XBP1s have relevant functions in sustaining gut physiology, where the genetic disruption of the pathway results in higher susceptibility to develop colitis and generates increased inflammation (Kaser et al., 2013), consistent with the fact that a polymorphism in the XBP1 gene increases the risk to develop inflammatory bowel diseases (Kaser et al., 2008).