It was previously demonstrated that in BC lung metastasis, miR-200b-3p transported by BC-derived exosomes was taken up by alveolar epithelial type II cells, and MDSCs were recruited to the lung to form PMN through the PTEN/AKT/NF-κB/CCL2 cascade and promote the spread of BC cells to the lungs 25. Here, PTEN is linked to breast cancer.