CXCL12 and myeloid sarcoma: While previous studies have demonstrated CXCR7 expression in human adult neurons [29], brain tumors [30] and human brain microvascular endothelial cells (HBMECs, [31]), we here demonstrate that CXCR7 is expressed on oligodendroglial cells in MS brain lesions and that its activation by CXCL12 leads to an acceleration of human glial maturation in culture as demonstrated by expression of oligodendrocyte lineage markers and enhanced morphological maturation.