PDCD1 and cancer: In addition, we also looked for correlation analysis between common immune checkpoint-associated marker genes and PTGES3, finding that PDCD1, CTLA4, HAVCR2, and TIGIT, and the expression of other classical immunosuppressive genes showed significant correlation over a wide range of cancers including LIHC, suggesting that there was a potential regulation of PTGES3 expression in the immune function of HCC (Figure 4E).