ACKR3 and central nervous system cancer: CXCL12 has higher affinity for the receptor CXCR7 (Esencay et al., 2013) whose high expression correlates with poor glioblastoma patient survival (Deng et al., 2017) and similarly to CXCR4 activation, triggers glioma proliferation and invasion (Liu et al., 2015).