CXCR4 and breast cancer: The power of CXCR4 asa marker for lymph node metastasis can be greatly increased by concurrentlyexamining the expression of additional markers such as VEGF, MMP-9, and CCR7 [38, 56].Furthermore, CXCR4 is also one of a subset of markers (the others are uPAR,S100A4, and vimentin) that define highly aggressive and invasive breastcarcinoma cells that are associated with malignant pleural or peritonealeffusions in breast cancer patients [57].