TGFB1 and hepatocellular carcinoma: It has been shown that TGF-β can induce immune escape by upregulation of the expression of PD-1 and cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) on T lymphocytes in HCC to attenuate the cytotoxicity of T lymphocytes for HCC cells both in vitro and in vivo [13].