['Epithelial-mesenchymal transition (EMT) not only initiates invasion and metastasis of tumors, but also induces multidrug resistance in tumor cells. Our experiment analyzed the dependability between breast cancer resistant protein (BCRP) and EMT in breast cancer to explore the effect of EMT on BCRP-mediated multidrug resistance.', 'The expressions of BCRP and transcription inhibitor Snai1 (Snail) in breast cancer were detected by immunohistochemistry. The eukaryotic expression vector pCDNA3.1-Snail was constructed and then transfected into human breast cancer cell line MCF-7. Snail, epithelial marker gene E-cadherin, interstitial marker gene Vimentin, multidrug resistance protein BCRP, and relative drug resistance were measured by immunofluorescence, Western blot, real-time polymerase chain reaction (PCR), and MTT assay.', 'Immunohistochemistry showed that Snail was highly correlated with BCRP in breast cancer. Immunofluorescence, Western blot, real-time PCR revealed that compared with parent cell MCF-7, after transfected with Snail, the expression of E-cadherin in MCF-7 decreased, but Snail, Vimentin, and BCRP increased. MTT displayed that the relative drug resistance increased to 9.93.'] Is multidrug resistance in breast cancer cells during epithelial-mesenchymal transition modulated by breast cancer resistant protein?