Thirdly, additional animal models of colitis, particularly of chronic disease, need to be examined; for example, trinitrobenzene sulfonic acid (TNBS) induced colitis, or adoptive transfer of CD4+CD45RBhigh T cells into recombinase-activating gene (rag)-1 deficient (rag1−/−) mice. The gene discussed is RAG1; the disease is colitis.