Flubendazole synergizes with vinblastine. The effects of increasing concentrations of flubendazole in combination with vinblastine (A), colchicine (B), cytarabine (C), or daunorubicin (D) on the viability of OCI-AML2 cells. Cell viability was measured by the MTS assay after 72 hours of incubation. Data were analyzed with Calcusyn software as described in “Methods.” CI versus fractional effect (Fa) plot showing the effect of the combination of flubendazole and vinblastine, colchicine, cytarabine, or daunorubicin. CI < 1 indicates synergism. One of 2 representative isobologram experiments performed in triplicate is shown.