We found that immune checkpoint-related genes commonly used in liver cancer immunotherapy, including PD-L1, PD1, PD-L2, CTLA-4, TIGIT, and TIM-3, were significantly upregulated in C2 (Fig. 6A–F), further suggesting the existence of an immunosuppressive microenvironment in C2 and that immunotherapy could reverse this immunosuppressive state. This evidence concerns the gene TIGIT and liver cancer.