As shown in Figure 4, different sites of the DNA methylation of KRAS are less expressed in tumors than in normal samples in the LUAD and PAAD, and increased in READ and COAD (Figure 4A–D, Table 3), which is consistent with the mRNA expression level and therefore implies the potential important connection between DNA methylation and gene expression. This evidence concerns the gene KRAS and pancreatic adenocarcinoma.