Induction of apoptosis in CML cells. (A) CML CD34⁺ cells (n = 5) were analyzed at 24 hours of drug exposure. The viable cell count (□) is expressed as a percentage of untreated (cell count %). The percentage of cells staining positive for 7-AAD (▴) is expressed on the y-axis (% cells apoptotic). Results represent the mean ± SEM with predicted dose-response curves. (B) CML CD34⁺ cells (n = 3) cultured in SFM+5GF and the viable cell count (× 10⁴ cells/mL) established at each time point as described. Results illustrated are untreated (□), and treated with 4nM (▴), 8nM (▾), and 16nM (■) bortezomib and are expressed as mean ± SEM with connecting lines. (C) Representative example of Western blot of CML CD34⁺ cells untreated (ND) or exposed to 10 or 20nM bortezomib (10,20) or 150nM dasatinib (Das) for 24 hours. The lower band represents the apoptosis-related PARP cleavage product. (D) CML CD34⁺ cells (n = 3) cultured for 24 hours in SFM+5GF and analyzed by flow cytometry to assess the percentage of cells with detectable active caspase-3 (mean ± SEM).