PDCD1 and hepatocellular carcinoma: The translation of CAF into HCC is mediated through hepatocyte proliferation and migration, neo-angiogenesis, and inhibition of cellular apoptosis [20,21,22,23], including the upregulation of IL-6/progranulin/mTOR signaling cascade, increased expression of co-inhibitory molecules programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1) and cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) [24,25].