Finally, seven proteins from the above 30 proteins were screened for differential expression in non-tumor and tumor tissues of HCC clinical samples by |log2 (fold change) |≥ 1 and the BH-adjusted P value < 0.05, Mothers against decapentaplegic homolog 2 (SMAD2), tyrosine-protein phosphatase non-receptor type 1 (PTPN1), Proliferating cell nuclear antigen (PCNA), monofunctional C1-tetrahydrofolate synthase, mitochondrial (MTHFD1L), Lysophospholipid acyltransferase 7(MBOAT7), Fatty acid-binding protein 5 (FABP5) and Agrin (AGRN) (Supplementary Fig. 6). Here, SMAD2 is linked to hepatocellular carcinoma.