ACKR3 and cancer: The CXCL12/CXCR4 signaling is composed of the chemokine CXCL12 (also called SDF-1 for stromal cell-derived factor 1) and its receptors CXCR4 and CXCR7, playing pivotal roles in the cell migration, angiogenesis, proliferation, and survival of many cancer cells, including SACC [22, 23].