KRAS and pancreatic ductal adenocarcinoma: Considering that oncogenic mutations of K-Ras are frequently observed in the vast majority of human pancreatic cancer cases [16], we next tested if the findings from our proteomic analysis in cell lines could be verified in pancreatic tumor samples, using a pancreatic cancer tissue arrays containing 80 pairs of pancreatic ductal carcinoma and the adjacent normal pancreatic tissues.