CXCL12 and neoplasm: In the tumor stroma, CAFs produce and secrete several factors such as extracellular matrix proteins (i.e., collagen I, III, IV), matrix metalloproteinases (MMPs), proteoglycans (i.e., laminin, fibronectin), chemokines (i.e., CXCL1, CXCL2, CXCL8, CXCL6, CXCL12/SDF1, CCL2, and CCL5), vascularization promoting factors (i.e., PDGF and VEGF), and other proteins that affect tumor cells’ proliferation, invasiveness, and survival (i.e., TGF-β, EGF, HGF, and FGF) (39).