Besides pancreatic cancer, cell cycle was the common biological function of differentially expressed genes in GO and KEGG, which involved several genes including BUB1, BUB1B, CCNA2, CCNB2, CCND2, CDC20, PLK1, TGFB2 and TTK. It is found that BUB1 is a remarkably altered gene in CD4+ peripheral blood cells of pancreatic adenocarcinoma patients compared with healthy volunteers [45]. Here, PLK1 is linked to pancreatic adenocarcinoma.