Fig. 4.

Extracellular vesicles-mediated ABCB1 protein transfer confers a transient resistant phenotype to sensitive cancer cells. A-B Cytotoxicity of Dox or DDP in the indicated cell lines is determined by MTT assay. C Effect of ABCB1 inhibitor verapamil on the cytotoxicity of Dox in the indicated cell lines is showed. D-G Intracellular accumulation of Rho-123 or Dox in the indicated cell lines is measured by flow cytometric analysis. H-K A long-term investigation of the accumulating level of Rho-123 or Dox in Aq-MDR cells is showed by flow cytometry. L The chemoresistance of Aq-MDR cells to Dox is declined gradually over time, monitoring by a long-term following MTT assay. M-N The protein expression of ABCB1 in Aq-MDR cells decreased with the cultured time, but mRNA level of ABCB1 did not alter. Values are means ± SD for three different experiments. * = P < 0.05, ** = P < 0.01