Implication of 4E-BP1 protein dephosphorylation and accumulation in pancreatic cancer cell death induced by combined gemcitabine and TRAIL

a Sensitivity of cells to gemcitabine was assessed by MTT assay. Cells were treated with increasing amounts of gemcitabine (0.001–1000？μM) for 24？h (n？=？4). b Sensitivity of cells to TRAIL was assessed by MTT assay. Cells were treated with increasing amounts of TRAIL (0.001–1000？ng/ml) for 4？h (n？=？4). c–e Sensitivity of cells to gemcitabine and TRAIL combination treatment was assessed by MTT assay. Cells were treated with increasing amounts of gemcitabine (0.1–100？μM) for 24？h (n？=？4) and/or 10 or 100？ng/ml TRAIL for 4？h for BxPC-3 and MIA PaCa-2 cells and 6？h for PANC-1 cells (n？=？4). All experiments were repeated three times and data are provided as means？±？SEM (one representative experiment is shown). P-values were calculated using Student’s t-test to determine the statistical significance of the difference between a, b untreated cells and cells treated with either 1000？μM gemcitabine or 1000？ng/ml TRAIL, respectively (ns: P？>？0.05, *P？<？0.05, **P？<？0.01) and c–e cells treated with 100？μM gemcitabine and cells treated with 100？μM gemcitabine plus 100？ng/ml TRAIL (***P？<？0.001