Daunorubicin accumulation increases in the cells treated with siMDR1-loaded Lipid microbubble transfection. The experimental groups I to V were same as that described in figure 2. L2-RYC cells were seeded in 6-well plates. Daunorubicin was added to the final concentration of 7.5 μg/ml. After 30 min, Verapamil at the final concentration of 10 μg/ml was added to terminate pumping-out of Daunorubicin. L2-RYC cells without any treatment were set as negative control. (A) Red fluorescent cells was observed under microscope, cells in group IV (cells transfected with pSEB-siMDR1s showed green fluorescent indicated by white arrow with thin arrowhead) exhibited more red granular fluorescence in cytoplasm(indicated by white arrow), (B) Red fluorescent cells were sorted by flow cytometry, (C) The percentage of red fluorescent cells of different treated groups was displayed in a histogram. (*P < 0.05, vs other groups).