CXCL12 and cancer: CAFs can stimulate cancer growth and progression by secreting stromal cell-derived factor 1 (SDF-1)/C-X-C motif ligand 12 (CXCL12) [104, 105], transforming growth factor-β (TGF-β) [105], interleukin (IL)-8 [106], and IL-32 [107].