To further confirm the role of CXCR4 in the invasiveness of neuroblastoma cells towards mRPMI, all CXCR4 isoforms were blocked using 10 μM AMD 3100, a CXCR4 antagonist [37, 38], and the 47 kDa isoform was specifically blocked with an anti-47kDa CXCR4 neutralizing antibody. Here, CXCR4 is linked to neuroblastoma.