C, D. Analysis of the in vitro suppressive function of Tregs isolated from WT mice or age- and sex-matched USP44-/- mice (n=3/group/experiment). Tregs were mixed with CFSE-labeled responder naïve T cells from CD45.1+ C57BL/6 mice (n=3/experiment) for three days. CFSE dilution in CD45.1+ T cells was observed by flow cytometry and the percent suppression of responder cell proliferation by the co-cultured Tregs was determined. 