Response of ALL cells and normal HSCs to PTL. (A) Percentage of viable ALL cells after PTL treatment in 7 B-ALL patients (open symbols) and 3 T-ALL patients (closed symbols). PTL was used at a dose ranging from 0.5-10μM and viability was assessed at 20-24 hours by flow cytometry using annexin V and propidium iodide. Samples depicted with dashed lines are high minimal residual disease risk patients. (B) Viability of CD34⁺/CD38⁻ HSCs from normal BM treated with PTL (10μM) compared with untreated controls (n = 6).