Following T-cell transfer into RAG2−/− mice, Kalim et al. [17] further observed a diminished Th1 and Th17 and enhanced Treg cell differentiation in recipients of β5i/LMP7-deficient CD4+ T-cells, suggesting that differences in T-cell differentiation explain for the relative resistance of inhibitor-treated or β5i/LMP7-deficient mice to development of DSS-induced colitis. Here, RAG2 is linked to colitis.