CXCR4 and neoplasm: CXCL12 bound to its specific G protein-coupled receptor CXCR4 induces a plethora of downstream signaling events involving ERK1/2, RAS, PLC/MAPK, p38 MAPK, and SAPK/JNK, which are in turn responsible for various biological and pathological processes including angiogenesis and tumor metastasis49.