FIGURE 4.

Akt-2 but not Akt-1 is the downstream target of Cbl-b in regulating Foxp3 expression. (A) Naïve CD4⁺CD25⁻ T cells from WT, Akt-1^−/−, Cbl-b^−/−, and Cbl-b^−/−Akt-1^−/− mice in the presence or absence of Akt-2i (3 μM) were stimulated and cultured as in B, and the expression of Foxp3 in CD4⁺CD25⁺ T cells was determined. (B) Naïve CD4⁺CD25⁻ T cells from WT, Cbl-b^−/−, Akt-2^−/−, and Cbl-b^−/−Akt-2^−/− mice were stimulated with anti-CD3 (0.5 μg/ml) together with anti-CD28 and TGF-β as shown in Figure 1A, and the expression of Foxp3 in CD4⁺CD25⁺ T cells was determined. The data shown are one representative of two independent experiments.