Etoposide (50 μmol/L), Ara-C (100 μmol/L), and doxorubicin (50 μmol/L) induced apoptosis of HL-60/neo, U937, and Jurkat cells.

Cells were treated with the drugs at the indicated concentrations for 6 hours followed by incubation for 18 hours in drug-free medium. After these treatments, the percentage of apoptotic cells was determined by Annexin V staining followed by flow cytometry (A). Molecular events of apoptosis induced by etoposide, Ara-C, or doxorubicin (B). Cells were treated with the indicated drugs for 6 hours, and then cell lysates were obtained for Western analyses of procaspase-3, procaspase-9, cytosolic cyt c, and Bid protein. Alternatively, Western analysis of XIAP and survivin was performed on the cell lysates (C) (see “Results”).