CXCL12 and neoplasm: The CXCR4/CXCL12 axis has been described to regulate the localization of NK cells in the bone marrow (Bernardini et al., 2008) and seems to be of importance with respect to recruitment of NK cells to the tumor site in neuroblastoma and multiple myeloma (Hanna et al., 2003; Ponzetta et al., 2015).