To clarify the role of CD69+ Tregs in colitis, we generated a conditional CD69 allele in which exons 2 to 4 were flanked by loxP sites, and Foxp3YFP-CreCD69fl/fl or CD4CreCD69fl/fl mice were generated to conditionally knock out CD69 in Foxp3+ or CD4+ T cells by crossing CD69fl/fl mice with Foxp3YFP-Cre or CD4Cre mice (Figure S1A-B). Here, CD69 is linked to colitis.