FIG 7.

Fas is required for LtxA-mediated cell death. (A) Jurkat E6.1 cells and both Jurkat Fas^−/− clones were treated with various concentrations of LtxA for 24 h. Staurosporine (STS; 1 μM) was used as a positive control for cell death. (B to E) Jurkat E6.1 cells and Jurkat Fas^−/− clones were treated with LtxA at the indicated concentrations for 24, 48, or 72 h, and cell death was assessed via flow cytometry. Cytotoxicity was determined by annexin V/7-AAD staining and flow cytometry. Data represent the average from three independent experiments. Error bars represent SEM. The significance of differences between results for Jurkat E6.1 cells and those for each Jurkat Fas^−/− clone was determined using Student's t test. **, P ≤ 0.01; ***, P ≤ 0.001; ns, not significant.