Figure 4. Amphiregulin contributes to chemoresistance by activating the PI3K, Akt, and NF-kB signaling pathways. (A) Protein expression was examined by Western blot assay. (B, C) Cells were pretreated with a PI3K inhibitor (Ly294002, 10uM), an Akt inhibitor (Akt i, 10 mM), or an NF-κB inhibitor (PDTC, 10 mM; TPCK, 3uM) or transfected with p85, Akt, p65, or ABCB1 siRNA, followed by stimulation with cisplatin for 24 h. Levels of ABCB1 expression and cell viability were detected by qPCR and MTT assays. The results were obtained from 3 independent experiments and are expressed as the mean ± SEM. * p < 0.05; ** p < 0.01; *** p < 0.001 compared with controls; #p < 0.05; ##p < 0.01; ###p < 0.001 compared with cisplatin-treated controls.