These cell lines showed good correlation between the expression of the 47 kDa CXCR4 isoform and clinical aggressiveness, as well as in vitro invasiveness, suggesting that the 47 kDa CXCR4, up-regulated by MSC secretome may mediate metastasis of neuroblastoma into the bone marrow in vivo. The gene discussed is CXCR4; the disease is neuroblastoma.