CXCL12 and neoplasm: Tumor-associated macrophages account for about 50% of the tumours in TME and predominantly exhibit an M2 phenotype, regulating tumour growth, migration and angiogenesis by producing a plethora of growth factors, cytokines and ECM remodelling molecules (e.g., CCL2, CXCL12, CXCR4, TGF-β, VEGF, PDGF, COX-2, and metalloproteinases), which contribute to the progression of almost all tumours [25].