CXCL12 and cancer: Moreover, CAF-derived hepatocyte growth factor (HGF), stromal cell-derived factor 1 (SDF1), and transforming growth factor beta (TGF-β) promote the proliferation, invasion, and metastasis of cancer cells by activating various signalling pathways, such as the MAPK and PI3K/AKT pathways, as well as the TGF-β/SMAD pathway [12–14].