A potent inhibitor of Aurora B and C (Kis = 0.38 and 1.5 nM, respectively); >250-fold selective for Aurora B and C over Aurora A; inhibits proliferation of A549 lung cancer cells in vitro (EC50 = 7 nM); inhibits proliferation in a panel of 100 tumor cell lines (EC50s = <10 nM); inhibits histone H3 phosphorylation in a COLO 205 mouse xenograft model and induces tumor regression in an HL-60 mouse xenograft model; reduces tumor growth in 10 mouse xenograft models