TEK and neoplasm: CSF‐1 and TAM‐derived EGF promote the production of each other and form a positive circulation that magnifies the promotion effect.47 In addition, the anoxic microenvironment of tumours can up‐regulate the expression of hypoxia‐inducible transcription factors (HIF‐1 and HIF‐2) in TAMs, which subsequently helps to form tumour blood vessels, lymphatic vessels and vascular mimicry.48, 49 The expression of Tie2 increased during the chemotaxis of tumour tissues and the production of TAMs.49 TAMs also help to form the tumour immunosuppressive environment.