Jurkat cells (T-cell leukemia,human) treated with 10 μM of camptothecin for 4 hours(panel right) or untreated control(panel left). 1. Wash cells twice with cold PBS and then resuspend cells in 1×Binding Buffer at a concentration of 1×106 cells/ml. 2. Transfer 100 μl of the solution (1×105cells) to a 5 ml culture tube. 3. Add 5 μl of Annexin V-AF647. 4. Add 5 μl PI. 5. Gently vortex the cells and incubate for 15 min at RT (25°C) in the dark. 6. Add 400 μl of 1×Binding Buffer to each tube.Analyze by flow cytometry within 1 hr.