CD8A and hepatocellular carcinoma: Among the 22 types of immune cells we analyzed (Figures 7, 8), high TGF-β1 expression in HCC patients is positively correlated with regulatory T cells (Tregs), suggesting that high level of TGF-β1 may activate Tregs to suppress antitumor immunity by inhibiting the killing of HCC cells by antigen-specific CD8+ T cells, leading to poor prognosis (30, 37).