On the other hand, increased metastatic capacity of CXCR4 expressing NB cells and increased CXCR4 expression in metastatic NB tumour cells as observed by Zhang et al. [12], may be explained by the i.v, implantation of tumour cells, thus focussing on late and bypassing the initial steps of metastasis. Here, CXCR4 is linked to neuroblastoma.