FIP1L1-PDGFRA/T674I can be inhibited by AMN107 (nilotinib) but not imatinib mesylate. Growth inhibition of Ba/F3 cells expressing FIP1L1-PDGFRA/wt (A), and Ba/F3 cells expressing FIP1L1-PDGFRA/T674I (B) by imatinib mesylate and AMN107. Proliferation was measured using an MTT-based method by absorption of formazam at 490 nm. Measures were taken as triplicates after 48 hours of culture without and in the presence of inhibitor at the indicated concentrations. Values are expressed as mean values of growth inhibition from 3 independent experiments. For each experiment, measures were taken in triplicates. Bars indicate ± SE. OD indicates optical density. Induction of apoptosis by AMN107 in Ba/F3 cells expressing FIP1L1-PDGFRA/T674I (C). Annexin V–positive cells were measured after 48 hours of culture in the presence of AMN107 at the indicated concentrations. Two experiments were performed. Results of 1 representative experiment are shown. Inhibition of autophosphorylation in FIP1L1-PDGFRA/T674I transfected Ba/F3 cells (D). Cells were incubated without and in the presence of imatinib mesylate (left panel) or AMN107 (right panel) at the indicated concentrations. Cell lysates were subjected to sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). Blots were probed for phosphotyrosine and PDGFRA.