ACKR3 and rhabdomyosarcoma: Binding of CXCL12 or interferon-inducible T-cell alpha chemoattractant (I-TAC/CXCL11), the other known CXCR7 ligand, to CXCR7 activates PI3K and MAPK signaling in astrocytes, Schwann cells, gliomas, rhabdomyosarcoma, and pancreatic cancer cells [23-26].