In the DSS-induced colitis model, VPAC1 KO mice are resistant to DSS-induced colitis, whereas colitis is exacerbated in VPAC2 KO mice; PKA inhibitors reverse the impairment of DSS colitis in VPAC2 KO mice, suggesting that enhanced VPAC1 activity in VPAC2 KO mice may aggravate DSS colitis56 or is alternatively explained by the protective effects of VPAC2 during the development of DSS-induced colitis, since VPAC2 activation inhibits Th1 signals11. This evidence concerns the gene VIPR1 and colitis.