UTP inhibits the migration of leukemic cells via specific P2Y receptors. Leukemic cells from 5 patients (10⁶/mL) were preincubated for 24 hours in the presence of ATP, UTP, INS973 (a P2Y2R/P2Y4R agonist), or INS415 (aP2Y2R/P2Y6R agonist). Migration of leukemic cells was then tested using Transwell assays, as described in “Methods.” Transmigrated cells were counted under the microscope, whereas untreated cells were used as a reference. (A) Spontaneous migration of AML cells. The percentage of migrating cells in control samples was 15% ± 4%. (B) Migration of AML cells toward the CXCL-12 chemokine. The percentage of migrating cells in control samples was 22% ± 5%. *P < .05.