This compound concentration was selected for two reasons: (1) because these primary (MNC or CD34+lin−) cells cannot remain in culture for more than five days in the absence of any additional stimulus and (2) because this concentration is near the IC50 for B-ALL cell lines (Figure 1) and because in our previous studies with acute and chronic myeloid leukemias, 5 μM and 24–48 h of stimulation ware an efficient way to induce cell death in bulk or stem cell populations [10]. This evidence concerns the gene CD34 and chronic myelogenous leukemia, BCR-ABL1 positive.