Coadministration of 2-ME and the HDACIs, NaB and SAHA, induces apoptosis in U937, Jurkat, and HL-60 cells, and in AML, CML, and ALL blast samples. (A) U937, Jurkat, and HL-60 cells were treated with 0.5 μM 2-ME in the presence or absence of NaB (1 mM) or SAHA (1.5 μM) for 24 hours, respectively, after which the percentage of apoptotic cells was determined by annexin V/PI staining and flow cytometry as described in “Materials and methods.” (B-D) Blasts from 5 patients with AML, 2 patients with CML, and 1 patient with ALL were isolated as described in “Materials and methods.” After washing and counting, isolated mononuclear cells were treated with 1 μM 2-ME in the presence or absence of NaB (1 mM) or SAHA (1.5 μM) for 24 hours, respectively, after which the percentage of apoptotic cells was determined by annexin V/PI staining and flow cytometry as described in “Materials and methods.” (E) CD34⁺ cells were treated with 1 μM 2-ME in the presence or absence of NaB (1 mM) or SAHA (1.5 μM) for 24 hours, after which the percentage of apoptotic cells was determined by annexin V/PE staining and flow cytometry as described in “Materials and methods.” Values represent the means ± SD for 3 replicate determinations.