Inhibitory effect of 2 aurora kinase inhibitors against growth of multiple myeloma cells. (A) MM cell lines were exposed to increasing concentrations (shown in key at top of figure) of either VX-680 or ZK inhibitors for 72 hours, after which MTT assays were performed as well as trypan blue exclusion. Bar data are percent inhibition of growth in MTT assays (vs vehicle alone; ie, no VX-680 or ZK), mean of 3 separate experiments where SDs were all less than 5% of the mean. Numbers at the tops of the bars represent percent of cells nonviable above control baseline nonviable percent (5%-15%, mean of 3 experiments). (B) Cells were cultured for 72 hours with increasing concentrations of VX-680 (at 50, 100, and 500 nM with symbols designated as in A), after which trypan blue exclusion was used to assess viable cell yield. Data are percent inhibition of viable cell yield (vs vehicle control), mean of 3 separate experiments. Cell targets are ANBL-6 MM cells, ANBL-6 cells first treated with 1000 U/mL recombinant IL-6 (ANBL-6 + IL-6), ANBL-6 cells stably transfected with an activated N-RAS allele, primary myeloma cells obtained from 2 MM patients (PT #1 and PT #2), peripheral blood lymphocytes (PBLs) from 3 healthy donors (data are means of 3 assays), and isolated B-cell CLL cells from 3 leukemic patients (data are means of 3 separate assays).