Notch signaling partially affects the effector function of established effector CD8⁺ T cells. Mart-1–specific CD8⁺ T cell clone was activated as described for Figure 4 in the presence or absence of Notch signaling inhibitors (A,C-E: 10 μM GSI or vehicle control; B: DLL4-Fc or 5 μg/mL control IgG). (A,B) The frequency of cells secreting IFNγ and (C) the amount produced per cell was determined 24 hours later using intracellular cytokine staining and flow cytometry (n = 5 independent experiments). As a measure for cytotoxic capacity, (D) cell surface expression of CD107a and (E) lytic capacity of the T-cell clone in a flow-based cytotoxicity assay were determined. Shown are representative examples of 3 independent experiments.