For example, TTP directly binds to the IL-17 mRNA 3′ UTR to mediate mRNA decay.179 T cell-specific deficiency of TTP in mice results in spontaneous chronic skin inflammation and severe colitis with an increased Th17 responses and IL-17 production.180 In addition, Regnase-1 negatively regulates mRNAs of c-Rel, OX40, and IL-2 through cleavage of their 3′ UTRs in T cells.181,182 T cell receptor ligation relieves Regnase-1-mediated suppression of these Th17 genes via cleavage of Regnase-1 at R111 by paracaspase mucosa-associated lymphoid tissue (MALT). Here, IL17A is linked to colitis.