Effect of adaphostin on CLL B cells. (A) Examples of dot plots for CLL cells stained with annexin (x-axis) and propidium iodine (y-axis) assessed by flow cytometry demonstrating increased cell death as doses of adaphostin are escalated. Dots in the lower right quadrants represent early apoptotic cells, and dots in the upper right quadrants represent late apoptotic cells. (B) Dose response curves for CLL B cells isolated from patients (n = 29) cultured with increasing doses of adaphostin for 24 hours. Percent viable cells relative to control (vehicle alone) is expressed on the y-axis. (C) Mean dose response curve for samples from all 29 patients in panel A. Y bars indicate the standard error of the mean at each dose level. (D) Mean percent viable CLL B cells for samples (n = 12) cultured with 2.5 μM adaphostin or vehicle at 24, 48, 72, and 96 hours. Y bars indicate the standard error of the mean at each dose level.