PGR and metastatic neoplasm: Furthermore, Nectin4 was also overexpressed on metastatic cancers (Figure 1B), especially bone-metastasized triple-negative breast cancer (TNBC), which was without the expression of estrogen receptor, progesterone receptor and proto-oncogene Her-2, indicating that Nectin4 could be used as a good therapeutic target for both primary and metastatic tumors.