TGF‐β can polarise macrophages from an M1 phenotype, which typically promotes anti‐tumour responses, to an M2 phenotype that typically helps tumour growth via secretion of ARG1, NOS2, cyclooxygenase‐2 (COX‐2) and more TGF‐β.47, 83, 84. Here, NOS2 is linked to neoplasm.