3-Cl-AHPC-mediated apoptosis in leukemic cells assessed by flow cytometry. Leukemia cells of patient 1 (A) and patient 10 (B) were treated with 1 μM 3-Cl-AHPC (Aii,Bii) or vehicle alone (Ai,Bi) for 24 hours and harvested; then the percentage of apoptotic cells was determined by means of an Apo-Direct Kit. The percentage of apoptotic cells is indicated in the right hand corner in the vehicle-treated control (labeled C) and 3-Cl-AHPC-treated cells.