CXCL12 and neoplasm: As important components of the TME, CAFs secrete various soluble cytokines, chemokines, and other factors, including CXCL12, vascular endothelial growth factor (VEGF), and transforming growth factor β (TGF-β) through various paracrine mechanisms, which have diverse effects on tumor phenotype, and can have pro-tumor properties [33].