FOXP3 and diabetes mellitus: In immunocompetent NOD mice, the in vivo application of in vitro expanded Foxp3+BDC2.5+ Treg cells [38, 39], as well as Foxp3+BDC2.5+ Treg cells, generated in vitro either by ectopic expression of Foxp3 [20] or TGF-β-mediated induction of Foxp3 expression [40], can be effective in prevention or even reversal of spontaneously developing diabetes.