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. 2014 Dec 1;111(50):E5429–E5438. doi: 10.1073/pnas.1421438111

Fig. 6.

Fig. 6.

Paclitaxel induces MDR1 expression in TNBC cells. (A and B) Cells were treated with vehicle (V) or 10 nM paclitaxel, either alone (P) or in combination with 100 nM digoxin (P/D) or 1 µM acriflavine (P/A) for 4 d and RT-qPCR was performed to quantify MDR1 mRNA relative to 18S rRNA and normalized to V (mean ± SEM; n = 3). *P < 0.001 compared with V, and #P < 0.001 compared with P, by Student's t test. (C) Cells were treated as described above and immunoblot assays were performed. (D and E) Cells were treated with 10 nM paclitaxel for 4 d and sorted into ALDH− and ALDH+ populations. RT-qPCR was performed to quantify MDR1 mRNA relative to 18S rRNA and normalized to vehicle-treated ALDH− cells. *P < 0.001 compared with vehicle-treated ALDH− cells, and #P < 0.001 compared with paclitaxel-treated ALDH− cells, by Student's t test. (F) MDA-MB-231 subclones were treated with vehicle or 10 nM paclitaxel for 4 d and analyzed by RT-qPCR using primers specific for MDR1 mRNA relative to 18S rRNA with results normalized to vehicle-treated NTC (mean ± SEM; n = 3). *P < 0.001 compared with vehicle-treated NTC, and #P < 0.001 compared with paclitaxel-treated NTC, by Student's t test. (G) MDA-MB-231 subclones were treated with vehicle (V) or 10 nM paclitaxel (P) for 4 d and immunoblot assays were performed. (H) MDA-MB-231 cells were treated with vehicle (V), the MDR1 inhibitor verapamil (M; 50 µM), paclitaxel (P; 10 nM), or both paclitaxel and verapamil (P/M) for 4 d and Aldefluor assays were performed (mean ± SEM; n = 3). *P < 0.001 compared with V, and #P < 0.001 compared with P, by Student's t test.