Isobolograms for the effects of daunorubicin and SU11248 on cellular proliferation. Cells were incubated with daunorubicin, SU11248, or both for 72 hours and proliferation was assessed using an XTT-based assay. Results were analyzed using Calcusyn software for (A) MV4-11, (B) MOLM14, (C) BAF3 ITD FLT3, (D) BAF3 WT FLT3 + FL, and (E) BAF3 D835V FLT3 cell lines (concentration of agents are expressed in nM). Observations lie near the lines of equivalence, suggesting an additive effect for the combination SU11248 and daunorubicin on MV4-11 and MOLM14 cells. For the 3 BAF3-derived cell lines, the combination results are more clearly to the left of the lines of equivalence, suggesting a synergistic effect. The CI values are listed in Table 2. • indicates ED₅₀; ▪, ED₇₅; and ▾, ED₉₀.