Figure 4. Macrophage positive-feedback effect on tumour ECM stiffening.
Macrophages are recruited to the tumour stroma through CCL2 secretion and SMAD upregulation in CAFs. Once recruited, these macrophages secrete TGF-β which stimulates the production of collagen and LOX by the tumour stroma which in turn leads to fibrosis and tumour ECM stiffening.