RIPK1 and colitis: PAR2 has also been shown to mediate the activation of NF-kappa-B and the release of prostaglandin E,55,56 which are key mediators in immune responses in preclinical models of colitis and IBD.57–60 Genes associated with NF-kappa-B activation, such as Melb, Ripk1 and Hif1a,61–63 or with receptors of prostaglandin E (Pteger1 and Pteger4) were altered in wild-type mice compared to R38E-PAR2 mice after colitis.