Fig. 5.

Overexpression of Erk1/2 impairs the anti-cancer effects of crizotinib in NSCLC cells. (a) Cells were transfected with plasmids expressing constitutively activated Erk1/2 for 48 h, after which the cells were examined for the expression of phosphorylated and total Erk1/2 by immunoblotting. (b and c) After transfection with plasmids expressing constitutively activated Erk1/2, cells were treated with crizotinib for 48 h. Then, the cell viability (b) and quantification of the apoptotic rates (d) were determined by MTS assay and flow cytometry, respectively. (d) After transfection with plasmids expressing constitutively activated Erk1/2, cells were treated with crizotinib for 24 h, quantification of the relative cell populations in each cell cycle stage was analyzed by flow cytometry. *P < .05 compared with vehicle. Values were presented as mean ± SD of three independent experiments and compared using student's t-test.