Figure 4.

MRP5 protein expression in cells with acquired gemcitabine resistance. Indicated pancreatic cancer cell lines were adapted to increasing concentrations of gemcitabine as described in the Materials and Methods section. After culturing the cells at the indicated gemcitabine concentration for at least 14 days, membrane fractions were isolated from these cells and subjected to immunoblot analysis for MRP5 and β-actin. MRP5 protein expression was normalized to the corresponding immunoblot signal for β-actin on the same PVDF membrane. Representative immunoblot analysis each performed twice on samples from two independent experiments.