PDCD1 and hepatocellular carcinoma: In addition, HCC patients with elevated SMIM25 expression demonstrated significantly higher expression levels of immunosuppression-related genes (e.g., PDCD1, CTLA4, CD209) and cell proliferation-associated genes (e.g., CDK1, TTK, BUB1B) compared to patients with low SMIM25 expression (p < 0.05; Figure 2F).