(A–C) Colony formation assay in PEPT1-positive Capan-1 and SU.86.86 cells and PEPT1-negative MIA PaCa-2 cells. All three cell lines were cultured in the absence and presence of increasing concentrations of glibenclamide (0–250 µM) in three culture conditions i.e. complete medium at pH 7.5, complete medium at pH 7.5 plus 2 mM Gly-Pro, and complete medium at pH 6.5 plus 2 mM Gly-Pro.