Furthermore, TOB1 not only inhibits the proliferation of Th17 cells (23), but in inflammatory bowel disease, it also induces the expression of ID2 in CD4+ T cells via SMAD4/5 signaling, which suppresses the conversion of CD4+ T cells into Th1/Th17 cells, thereby inhibiting mucosal inflammation (24). This evidence concerns the gene CD4 and inflammatory bowel disease.