ARG1 and neoplasm: • Tumor cells produce GM-CSF→ PD-L1 expression in TAN via JAK/STAT pathway→ PD-L1+ TAN inhibit T-cell immunity (N2 TAN) • TAN suppress immune cells via Arginase-1, i-NOS • TAN recruit Treg via CCL17 • TAN→ ↑angiogenesis via MMP-9, VEGF