PECAM1 and breast cancer: These NPs effectively decreased microenvironment biomarkers such as TGF-β1, matrix metalloprotease 9 (MMP-9), and platelet and endothelial cell adhesion molecule 1 (PECAM1, also called CD31) related to metastasis, indicating that the NPs are effective nanocarriers of an oral drug to inhibit metastasis of breast cancer to the lung [51].