Expression and activation of FLT3 in leukemic cell lines—the FLT3V592A mutant expressed in MM1 and MM6 cells induces IL-3–independent growth in Ba/F3 cells.
(A) Expression of FLT3 on the surface of leukemic cells analyzed by flow cytometry after staining with an anti-CD135 antibody. Open histograms represent isotype control; filled histograms show fluorescence intensity of CD135. (B-C) Activation of FLT3 in leukemic cell lines analyzed by immunoprecipitation (IP) and blotting by anti-PY antibody with (+) or without (−) stimulation with FL. Blots were stripped and reprobed with a specific FLT3 antibody. As a positive control, Ba/F3 cells stably expressing an FLT3ITD mutant are shown in lane 1 (panel B). (D) Ba/F3 cells stably expressing FLT3ITD-W51 and FLT3V592A were seeded at a density of 4 × 104 cells/mL in the absence or presence of IL-3 (10 ng/mL). Viable cells were counted for up to 3 days by trypan blue exclusion. A representative result of 3 experiments with similar results is shown.
