Yu et al. showed that TNFα-activated mesenchymal stromal cells can recruit CXCR2+ neutrophils to tumor microenvironment, resulting in upregulation of MMP12 and other metastasis-related genes in tumor cells, such as MMP13 and TGFβ, that promoted breast cancer metastasis (Yu et al., 2017). The gene discussed is MMP12; the disease is breast cancer.