Fig. 6.

WBP2 mediates the upregulation of MDR1 in MCF-7 cells. The interaction between WBP2 and ERα were detected using antibodies against WBP2 (a) and ERα (b) by performing co-immunoprecipitation assay in control MCF-7 and WBP2-overexpressing MCF-7 cells. c ChIP assay was performed to determine the interaction between the half-ERE motif of MDR1 promoter region and ERα using anti-ERα antibody in control MCF-7 and WBP2 stable expression MCF-7 cells. d The association of ERα with the MDR1 promoter was confirmed by qChIP assay. e After pre-treated with fulvestrant for 48 h, cell viability was measured using MTT assay in control MCF-7/BT474 cells and WBP2-overexpressing MCF-7/BT474 cells under the treatment with 0.5 μM doxorubicin for 0, 24, 48 and 72 h. f The proposed model of WBP2-mediated drug resistance in ER-positive breast cancer cells. EGFP, control MCF-7 cells; EGFP-WBP2, WBP2-overexpressing MCF-7 cells. *P < 0.05, **P < 0.01