Some researchers have postulated that CXCR7 acts as a decoy receptor because of its inability to induce calcium mobilization, cell migration or integrin activation upon binding to CXCL12, [20, 23, 30] whereas others argue against this hypothesis due to the observed roles of CXCR7 in signaling activity and migration, particularly in tumor growth and metastasis [23, 31–33]. The gene discussed is ACKR3; the disease is neoplasm.