CXCR4 and neuroblastoma: Interestingly, we found that AMD3100, a synthetic CXCL12 antagonist known to block CXCR4 function [53], abrogated the enhanced invasiveness of NB cells pre-incubated with MSCs, suggesting that the CXCR4/CXCL12 axis played a pivotal role in the MSC-mediated migration of NB cells.