Fig. 5. Synergistic lethality of low-dose PLK1 inhibitor and microtubule polymerisation inhibitors. A. Tetraploid RKO cells were exposed to different doses of vincristine and cell survival was calculated after 72 h using a crystal violet assay. B. Tetraploid RKO cells were treated with different concentrations of Bi2536 and vincristine to evaluate the synergetic effect of the combination treatment. The red stars indicate the synergetic effect of the treatment condition. C. Tetraploid RKO cells were exposed to increased dose of colchicine and cell survival was calculated at 72 h using crystal violet assay. D. Combination treatment with Bi2536 and colchicine was performed to evaluate the synergetic effect of the combination treatment. The red stars indicate a synergetic effect for the treatment condition.