Wnt/β‐catenin pathway alters MDR of QBC‐939/5‐FU cells. (a) The drug susceptibility to chemotherapeutics (60 μM) of QBC939 and QBC939/5‐FU cells transfected with siβ‐catenin, or (b) after Wnt3a (50 nM) treatment for 6 h, compared to respective control. Equivalent amount of water served as vehicle for Wnt3a. (c) CyclinD mRNA expression in QBC939 and QBC939/5‐FU cells transfected with siCtrl or siβ‐catenin, with/without Wnt3a treatment. (d) Protein expression of β‐catenin and P‐gp in QBC939 cells after Wnt3a (50 nM) treatment for 6 h assayed by western blot. (e) Effect of ESC‐3 (10 μg/mL) on the drug susceptibility of QBC939/5‐FU cells to 5‐FU detected by MTT assays. Methanol‐0.01 M NaH2PO4 (70:30, v/v) served as vehicle. (f) Protein expression of β‐catenin and P‐gp in QBC‐939/5‐FU cells with/without ESC‐3 treatment in the absence/presence of Wnt3a (50 nM) for 24 h. *P < 0.05, **P < 0.01, ***P < 0.001. 5‐FU, 5‐fluorouracil; CDDP, cis‐diammineplatinum(II) dichloride; VCR, vincristine sulfate; MDR, multi‐drug resistance; MMC, mitogen enzyme C; P‐gp, P‐glycoprotein.