CXCR4 and osteosarcoma: Therefore, CXCR4 expression has been linked to tumor cell invasiveness (Wang et al., 2015; Song et al., 2015; Perissinotto et al., 2005; Sun et al., 2010) which is also expressed by osteoblasts and by malignant cells in osteosarcoma (Jung et al., 2006).