We found that checkpoint molecules such as PD-1, CTLA4 and LAG3, as well as markers of exhausted T cells such as CCR7, TIGIT, PTGER2, NT5E, IL7R, IFNG, CXCR5, CXCL10 and CD244 were associated with CLDN18 in HCC. The gene discussed is PTGER2; the disease is hepatocellular carcinoma.