CXCL12 production in NB cell lines and xenografts was low (mean concentration of CXCL12<180 pg/mg of protein) and did not significantly vary between either cell lines or derived tumors, suggesting that the CXCR7-mediated anti-proliferative effect is unlikely due to the presence of its ligand CXCL12 in such in vivo conditions. Here, CXCL12 is linked to neuroblastoma.