Rapamycin restores the sensitivity of FLT3-ITD-TKD–expressing cells to the FLT3 PTK inhibitor SU5614. Ba/F3 cells expressing FLT3-ITD (A) or FLT3-ITD-TKD (B) constructs were seeded at a density of 4 × 10⁴ cells/mL in the absence or presence of different concentrations of SU5614 without or in combination with 5 ng/mL rapamycin (R). Viable cells were counted after 72 hours by trypan blue exclusion. The growth of cells that were incubated without inhibitor was defined as 100%. Values represent means and standard deviations from 3 independent experiments.