XBP1 and colitis: These animals were more susceptible to dextran sodium sulfate- (DSS-) induced colitis, which is probably caused by multiple mechanisms including the absence of XBP1-mediated adaptive UPR, proapoptotic effectors such as CCAAT-enhancer-binding protein homologous protein (CHOP), cellular inflammatory response in the settings of IRE1α activation, and its downstream signaling [14].