Although cytokines appear to have a major role in driving inflammation in IBD,7 the epithelial barrier has also been proven to have a critical role in suppressing intestinal inflammation.50 Under basal conditions, Acer3−/− mice did not exhibit decreased intestinal epithelial barrier integrity (Supplementary Figure S3E), and these mice did not develop spontaneous colitis up to 8 months of age (Supplementary Figure S3F). The gene discussed is ACER3; the disease is colitis.