Apoptosis induced effect of simvastatin/tipifarnib measured by Annexin V/PI staining. HL60 and Jurkat cells were treated with simvastatin (4 μM) and tipifarnib (1 μM) alone and in combination for 72hr. Cells were then costained with Annexin and PI with subsequent flow cytometric analysis. A representative dot-plot is shown for each condition (A). AnnexinV+/PI− stained cells in the bottom right quadrant represent early apoptotic cells whereas late apoptotic or necrotic cells are located in the upper right quadrant with Annexin+/PI+ staining. In panel (B), representative figures of AnnexinV/PI staining of HL60 and Jurkat cells showing the sum of the percentages of early and late apoptotic cells. Results represent means of 3 independent experiments. *, P > 0.05, significantly greater than values for cells exposed to simvastatin or tipifarnib alone. SIM, simvastatin. TIP, tipifarnib.