There are significant differences in the expression and functions of HIF-1α and HIF-2α in IBD: HIF-1α exerts anti-inflammatory and protective effects by upregulating the expression of barrier-protective genes and antimicrobial peptides, whereas HIF-2α promotes epithelial cell-mediated inflammatory responses and proliferation, which are associated with chronic inflammation and carcinogenesis [33]. This evidence concerns the gene HIF1A and inflammatory bowel disease.