Consistent with the results obtained from the TCGA database, we found that the expression levels of HSPA5, EMC2, SLC7A11, HSPB1, GPX4, FANCD2, CISD1, FDFT1, SLC1A5, TFRC, RPL8, LPCAT3, DPP4, CS, CARS1, ATP5MC3, ALOX15, ACSL4 and ATL1 were higher in HCC tissues than in normal liver tissues, while the expression levels of CDKN1A, NFE2L2, MT1G, SAT1 and GLS2 were obviously lower in HCC tissues than in normal liver tissues (Supplementary Figures S1A,B). This evidence concerns the gene DPP4 and hepatocellular carcinoma.