CXCL12 and neoplasm: Fibroblasts remodel extracellular matrix (ECM) at the pre-metastatic niche, a tumor growth-favoring microenvironment developed in the absence of neoplastic cells13–15, secreting inflammatory cytokines and growth factors such as CXCL12, TGF-β, S100A4, and expressing fibronectin and matrix metalloproteinases (MMPs)16.