A potent Eg5 inhibitor (IC50 = 6 nM); selective for Eg5 over a panel of 8 kinesins (IC50s = >100 μM) and a panel of 224 kinases at 10 μM; induces time-and dose-dependent cell death in HL-60, Jurkat, OCI-AML3, U937, and MOLM-13 leukemic cells; induces cell cycle arrest at the G2/M phase in a p53- and XIAP-independent manner in OCI-AML3 cells; inhibits blast colony formation of bone marrow samples derived from human AML patients; completely eliminates tumors in the RPMI-8226 multiple myeloma and HL-60 and MV4-11 AML mouse xenograft models at 20 mg/kg per day ,