Nutlin-pretreated MSCs exhibit reduced protection of FLT3/ITD AML cells from FI-700–induced mitochondrial apoptosis. Normal MSCs (N-MSC) were pretreated with 10μM Nutlin-3a (N3a) for 24 hours. MOLM-13 cells were treated with 800nM FI-700 for 24 hours in the presence or absence of MSCs. Bax conformational change (A) and activation of caspase-3 (B) were analyzed by flow cytometry. Representative flow cytometry results are also shown. Asterisk (*) indicates significance at P < .05 (1-way ANOVA/Tukey). (C) Mcl-1, Bcl-XL and survivin levels were determined by Western blotting. Intensity of the immunoblot signals was quantified and the relative intensity compared with β-actin was calculated.