To assess the role of Th1-like Tregs n the development of colitis, we crossed FoxP3eGFP−CreRosa26tdRFP mice with mice carrying floxed TBX21 alleles (TBX21fl/fl) to obtain a Treg-specific Tbet conditional knockout mouse (from here on indicated as FoxP3CreTBX21fl/fl). Here, TBX21 is linked to colitis.