Pimozide induces apoptosis of CML cells. (A) KU812 and K562 cells were treated with the indicated concentrations of pimozide for 48 hours, after which viable cell number was measured using an ATP-dependent bioluminescence assay. Data are representative of 3 independent experiments. (B) Unfractionated bone marrow mononuclear cells harvested from 2 untreated CML patients were treated with pimozide at the indicated concentrations for 48 hours, and viable cell number was determined. (C) KU812 cells were treated with vehicle or pimozide (5μM) for 48 hours, after which annexin V/propidium iodide staining and flow cytometry were performed. Among vehicle-treated cells, 7.6% showed annexin V staining, whereas among pimozide-treated cells 17.3% were annexin V positive. (D) Peripheral blood mononuclear cells harvested from 7 healthy persons were treated with the indicated concentrations of pimozide for 48 hours, after which viable cell number was measured using an ATP-dependent bioluminescence assay. Data are mean ± SEM.