ACKR3 and neuroblastoma: Other reports revealed that CXCR4 and CXCR7 expression patterns on NB tumors are distinct or even opposed, as scarce and preferential expression of CXCR7 was observed in neural-associated compartment of differentiated and matured tumors [35], while CXCR4 expression was associated to highly aggressive, undifferentiated tumors [13,36].