CXCL12 and neuroblastoma: In addition to a possible paracrine effect on tumour growth, the high levels of CXCL12 measured in the primary site (adrenal gland), represents a unique situation to NB where CXCL12 in the adrenal gland could also serve to retain the malignant cells in the primary site, rather than encourage them to metastasise [9].