The heatmap and boxplots revealed that the expression of some genes, including SIGLEC15, LAG3, PDCD1, CTLA4, TIGIT, HAVCR2, CD274, and PDCD1LG2, was higher in C2 HCC patients than in C1 patients (Figure 4C,D). The gene discussed is PDCD1; the disease is hepatocellular carcinoma.