To induce experimental colitis, Rag1 -/- and Rag2 -/- mice (n = 5 of each per group) were injected i.p. with either a PBS vehicle solution or 5 × 105 proinflammatory naïve T cells isolated from wild-type animals of the same genetic background (C57BL/6). This evidence concerns the gene RAG1 and colitis.