TGFB1 and hepatocellular carcinoma: Mechanistically, TAMs promote tumor growth, invasiveness, metastasis, and EMT by acting as myeloid-derived suppressor cells (MDSCs) that suppress CD8+ cytotoxic T lymphocyte (CTL) responses and by producing IL-6, programmed death-ligand 1 (PD-L1), granulocyte-colony stimulating factor (G-CSF), TNF-α, TGF-β and VEGF that accelerate HCC cell proliferation and invasion (13, 65–67).