All the differentially expressed genes were showed in Supplementary Table S1, and the results indicated that 104 genes such as ADAMTS2, BIRC5, MYC, ID1, VIM, CDH2, SMAD7, AXIN2, FAP, CAP1, SNAI1, CD59, ANXA8, YAP1, DUSP4, SOX2, KRT9, KRT13 et al. were enriched in “metastasis group” and had high expression in pancreatic ductal adenocarcinoma. Here, KRT9 is linked to pancreatic ductal adenocarcinoma.