Cell viability assay

Colo357, Capan-1 and MIA-PaCa-2 cells (2,000 cells/well) were plated into each well of multiple 96-well plates and cultured for 24 h at 37°C in DMEM or RPMI-1640. Cells were then treated with 0, 0.25, 0.5, 1, 2 or 4 µM of Adriamycin (Sigma-Aldrich; Merck Millipore, Darmstadt, Germany). Cell viability was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay. Cells were incubated with MTT for 2 h at 37°C. Following removal of the media containing MTT solution, the remaining dark blue formazan crystals in each well were dissolved in dimethyl sulfoxide. The absorbance was determined with a microplate reader. Each experiment was performed in triplicate.