Impaired Th2 cell differentiation in Stat5a^−/− T cells is cell-cycle independent.

Splenocytes from DO10⁺ mice (A,C,E) or DO10⁺Stat5a^−/− mice (B,D,F) were labeled with CFSE and stimulated with platebound anti-CD3 mAb for 60 hours in nonpolarizing condition. Intracellular staining for cytokines was performed as described in “Materials and methods.” Shown are representative FACS profiles (panels A,B for the intensity of CFSE; C,D for IL-4 versus CFSE staining; and E,F for IFN-γ versus CFSE staining of CD4⁺ T cells) from 4 mice in each group.