D. (left panel) iTreg were polarized from human naïve CD4+ T cells over 7 days (n=3 donors /experiment) receiving control (shCK), or shRNA knockdown constructs targeting USP44 (shUSP44-1, -2), or USP7 (shUSP7-1, -2), or both shRNA constructs. Freshly isolated nTregs were treated with either control or shRNA constructs. After transduction with lentivirus for 48 hours, cells were harvested and run SDS-PAGE gels. Protein levels were visualized by immunoblotting using antibodies specific for FOXP3, USP44, USP7 and GAPDH. Shown are representative findings from 3 independent experiments (biological replicates). 