Identification of differentially expressed genes (DEGs) in PDAC using RNA-seq and microarray data. (A–C) Scatter plots of FPKM values for gene expression of PDAC versus PDAC (A), non-tumor pancreas versus non-tumor pancreas (B), and PDAC versus matching non-tumor pancreas (C). Pearson correlation coefficients are shown above the corresponding scatter plots. (D) Heatmap of 1371 DEGs identified from the comparison between six PDAC and six non-tumor control specimens (p < 0.05 and |log2FC| > 0.5). (E, F) Venn diagram of DEGs identified from previous published microarray studies of PDAC versus non-tumor controls using two types of Affymetrix microarray platforms. Overlapping upregulated DEGs (n = 795) (E) and downregulated DEGs (n = 252) (F) are shown. (G) Heatmaps and hierarchical clustering of all PDAC specimens versus non-tumor controls from three independent groups clearly show that these 1047 DEGs can distinguish PDAC from non-tumor pancreas specimens FC, fold change; FPKM, fragments per kilo-base per million mapped reads; PDAC, pancreatic ductal adenocarcinoma; RNA-seq, RNA sequencing.