Figure 1: The roles of tumor-associated macrophages (TAMs) in liver cancer. TAMs promote hepatocellular carcinoma (HCC) growth, angiogenesis, invasion, and metastasis, as well as the suppression of antitumor immune response by interacting with both stromal and cancer cells within the tumor microenvironment. TAMs are recruited in HCC milieu by M-CSF, CCL2, VEGF, and TGFβ, and they, in turn, release many cytokines, chemokines and growth factors, which are implicated in such crosstalk. In particular, IL-6 and TGFβ favor tumor growth, whereas TNFα, OPN, MMPs, and IL-6 are involved in invasion and metastasis; TGFβ, in concert with IL-10, promotes the suppression of antitumor immune response. Finally, angiogenesis is induced by several molecules, including VEGF, EGF, PDGF, and TGFβ. Refer to the text for abbreviations.