CXCR4 and pancreatic neoplasm: Chemokine (C-X-C motif) ligand 12 (CXCL12), also known as stromal cell-derived factor 1 (SDF-1), which is produced by carcinoma-associated fibroblasts (CAFs), stimulates pancreatic cancer cell proliferation, recruits regulatory T cells (Tregs) and promotes desmoplastic alterations in the surrounding stroma through the CXCR4/CXCL12 axis [15–17].