Cytotoxic activity of FSP26-specific CTL clones 2, 3, and 4. No significant increase in CTL reactivity upon addition of FSP26 is seen. Reactivity against HCT116 cells [HLA-A0201+, Caspase-5(-1)] with (solid rhombus) and without (open rhombus) exogenously added FSP26 is shown. Killing of targets is depicted at different effector-to-target cell ratios (E:T ratios). All results are displayed as the mean and standard deviation from three replicate wells. Lysis was measured after 12 h.