SIRPA and neoplasm: The immune microenvironment of HCC is composed of immunosuppressive cells (e.g., myeloid-derived immunosuppressive cells, tumor-associated macrophages, and regulatory T cells), immune effector cells (e.g., CD8+ cytotoxic T cells and effector CD4+ T cells), the cytokine milieu (e.g., IFN-γ, TGF-β, TNF, etc.), and tumor cell-intrinsic signaling pathways (e.g., MCSF-CSF-1R and CD47-SIRPα) [153].