Point mutations in the JM domain of FLT3 induce resistance to apoptosis after IL-3 withdrawal. (A) Ba/F3 cells stably transduced with FLT3-WT, FLT3-ITD (W51, NPOS, W78), FLT3-TKD (D835Y, D835V) or FLT3-JM-PM (FLT3-V592A, FLT3-V579A, FLT3-F594L, and FLT3-F590GY591D) were seeded at a density of 1 × 105 cells/mL and grown for 48 hours in the presence or absence of IL-3. Cells were then analyzed by flow cytometry after staining with annexin V-PE and 7-AAD. All FLT3-JM-PMs showed a significantly lower percentage of apoptotic cells compared with FLT3-WT after IL-3 withdrawal (*P < .05). FLT3-ITDs and FLT3-TKDs protected cells from undergoing apoptosis. (B) Cells were cultured in the presence or absence of IL-3 for 24 hours and analyzed by flow cytometry after staining of nuclei with propidium iodide. FLT3-JM-PMs showed a significantly lower percentage of hypodiploid nuclei compared with FLT3-WT (*P < .05). SD is indicated.
