It was reported (Hsu et al., 2019) that CXCL17 secreted by primary BC can increase the accumulation of MDSCs (CD11b+Gr1+) in the lungs, resulting in the production of high levels of PDGF-BB, which leads to the enhancement of angiogenesis in lung tissues before the arrival of BC cells, laying the foundation for BC lung metastasis. The gene discussed is CXCL17; the disease is breast cancer.