In agreement with our results, several reports indicate that BM‐MSCs secrete high levels of SDF‐1 but express low levels of CXCR4, whereas OS cells release small amounts of SDF‐1 but express elevated levels of CXCR4, crucial to promote the metastatic spread of the tumour to the lung (Perissinotto et al., 2005; Ponte et al., 2007; Yu et al., 2015). The gene discussed is CXCR4; the disease is neoplasm.