Studies have shown that tumor necrosis factor-α activated CXCR2 ligands (CXCL1, CXCL2 and CXCL5) expressed by MSCs can effectively aggregate and migrate CXCR2+ neutrophils into tumor and significantly promote tumor metastasis (Hernanda et al., 2014). Here, CXCR2 is linked to neoplasm.