Mice deficient in the transcription factor, X-box-binding protein 1 (XBP1), a key component in the activation of the ER stress response, spontaneously develop small intestine inflammation, which displays a patchy pattern, is not granulomatous, and has severity varying from the presence of mild polymorphonuclear infiltrates in lamina propria to the presence of crypt abscesses and ulcerations (100). The gene discussed is XBP1; the disease is abscess.