IFN- enhances IL-2–induced STAT1 and STAT5 binding to the IRF-1 GAS. T cells were left untreated or treated with IFN- (100 IU/mL) for 24 hours. The cells were washed and resuspended in fresh medium, and different concentrations of IL-2 (0, 3, 10, or 30 IU/mL) were added. After 30 minutes of incubation, nuclear extracts were prepared and analyzed in EMSA with IRF-1 GAS probe. The experiment was repeated three times with similar results.