Figure 1. FKB eliminates human leukemic cells by apoptosis. A. FKB reduces viable cell numbers of human leukemic cell lines. HL-60, K562, MOLT4, and CEM1 cells were exposed to the designated concentrations of FKB for 0, 48, and 72 h. Cell viability was assessed by an MTS assay. The results displayed are the relative cell viability to that of the vehicle control (V). When the results are statistically significant compared with vehicle controls at 72 hours, the results are marked in the figure. In HL-60 cells at 48 h, **V vs. F 15 μM, *F 5 μM vs. F 15 μM; and at 72 h, **V vs. F 15 μM, *F 5 μM vs. F 15 μM. In K562 cells at 72 h, *V vs. F 24 μM, *F 3 μM vs. F 24 μM, and *F 6 μM vs.F 24 μM. In CEM1 cells at 48 h, ***V vs. F 5 μM, ***F 1 μM vs. F 5 μM, *F 2 μM vs. F 3 μM, ***F 2 μM vs. F 5 μM, and *F 3 μM vs. F 5 μM; and at 72 hours, *V vs. F 3 μM, ***V vs. F 5 μM, **F 1 μM vs. F 5μM, and **F 2 μM vs. F 5 μM. *p<0.05, **p<0.01, ***p<0.005. Data are means±SEM. N=4 for HL-60, 2 for K562, 4 for MOLT4, and 2 for CEM1. Each experiment was performed as three independent experiments with six replicates each. B. FKB promotes apoptosis in HL60 cells. HL-60 cells were treated with 10 or 15 μM FKB for 24, and 48 h and then the apoptotic cells were assessed using FITC-conjugated AV and PI by flow cytometry. Ethanol was used as a positive control for the last 30 min while the negative control was not treated with any reagent. The results are representative of at least 3 independent experiments.