CTLA4 and liver cancer: 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.