AMD3465 inhibits migration and enhances proaptotic effect of ara-C in primary AML.(A) AMD3465 suppresses SDF-1α–induced (n = 7 samples) and MS-5-induced (n = 14 samples) migration of primary AML cells. The error bars represent SEM. (B) Stromal cells protect primary AML cells (n = 21) from spontaneous and chemotherapy-induced apoptosis. Primary AML cells cultured alone (□) or cocultured with stroma (, ■) were treated with 3 μM ara-C for 24 hours. The percentage of the apoptotic cells (annexin V–positive cells) were analyzed by flow cytometry. (C) AMD3465 sensitized primary AML cells (n = 20) cocultured with stromal MS-5 cells to ara-C–induced apoptosis (24 hours). Apoptotic cells were detected by annexin V flow cytometry after gating on CD34⁺ leukemic cells. The specific apoptosis was calculated by the formula: % specific apoptosis = (test – control) × 100/(100 – control).