In particular, mice with Xbp1-deficient IECs develop spontaneous enteritis and display ER stress with high level of the chaperone grp78 and C/EBP homologous protein (Chop), Paneth cell loss, and reduced globlet cell number and size, compromised response to pathogenic bacteria (i.e., L. monocytogenes), and they are more susceptible to DSS colitis (120). This evidence concerns the gene DDIT3 and colitis.