Amiloride enhanced the long-term growth inhibition of erlotinib in Bxpc-3, PANC-1, Aspc-1, and CFPAC-1 human pancreatic cancer cells. Cells were treated with 0.5% DMSO, amiloride (30 μmol/L), erlotinib (3 μmol/L), or their combination in triplicate. Colonies were stained with Giemsa and photographed. Experiments were repeated three times. (A) A representative photograph is shown. (B) Colonies consisting of greater than 20 cells were counted as shown. Mean±SD. n=3. bP<0.05, cP<0.01 compared with control. eP<0.05, fP<0.01 compared with groups treated with erlotinib alone.