Notably, colitis induced by transfer of WT T cells into TNFf/f x Vil-Cre×Rag1−/− and TNF−/−×Rag1−/− recipients was accompanied by increased proliferation of epithelial cells (Fig. 9I, J), in contrast to Rag1−/− mice reconstituted with WT T cells. This evidence concerns the gene RAG1 and colitis.