RAG1 and colitis: To further confirm the regulatory role of SHP2 in Treg differentiation, we established an adoptive transfer colitis model by transferring CD4+CD25−CD45RBhigh T cells from SHP2f/f and CD4‐Cre;SHP2f/f mice to Rag1−/− mice, thereby isolating the influence of CD4+ T cells on disease onset and progression.