Expression and functional relevance of MDR1 (P-glycoprotein) in CEM/AKB cells.

<p>A) CEM/AKBMDR1 mRNA expression in ZM447439 resistant CEM cells as determined by real-time PCR. Expression is displayed as relative ΔΔCt values of CEM, CEM/AKB4, CEM/AKB4 and CEM/AKB4 cells compared to that for CEM/VCRR cells with Ct values normalised to the cyclophilin-A gene (PPIA). Error bars represent the SEM of three independent experiments. B) Cytotoxicity assays of doxorubicin against CEM and CEM/AKB4, 8, and 16 cells.</p

Mitotic index of CEM and CEM/AKB4 cells in the presence and absence of 4 µM ZM447439.

<p>*Percentages of mitotic cells were calculated after counting at least 1000 cells in three independent experiments.</p

Proliferation timecourse of CEM and CEM/AKB cells in the presence and absence of ZM447439.

<p>Cells were grown either in vehicle alone or in 4 µM ZM447439 and proliferation was determined at indicated timepoints as the corrected absorbance using the Alamar blue assay measured spectrophotometrically. Error bars represent the SEM of three independent experiments.</p

Levels of phosphorylated Histone H3 in CEM and CEM/AKB cells in the presence or absence of 16 µM ZM447439.

<p>Levels of phosphorylated Histone H3 in CEM and CEM/AKB cells in the presence or absence of 16 µM ZM447439.</p

Induction of apoptosis in CEM and CEM/AKB cells.

<p>A) Levels of cleaved PARP in cells treated with indicated concentrations of ZM447439 for 24 h as determined by western blot. B) Proportion of apoptotic cells in both untreated and CEM and CEM/AKB cells treated with 16 µM ZM447439 for 24 h.</p

Resistance levels of CEM/AKB4.

<p>(A) Plot of cell viability against concentration of ZM447439 for both CEM/AKB4 and parental CEM cells as determined by cytotoxicity assay. (B) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0030734#s3" target="_blank">Results</a> of the same experiment performed in the presence of the P-glycoprotein inhibitor verapamil. Points are the means, and bars are the SEM of at least three independent experiments.</p

Relative resistance of CEM/AKB4 cells to cytotoxic agents compared to parental CCRF-CEM cells.

a<p>Determined by dividing the IC₅₀ for the resistant (CEM/AKB4) cell line by the IC₅₀ of the parent (CEM) cell line.</p