To explore differences in seeding and colonization potential we analyzed expression of mammary epithelial transcripts (CK19, MGB1), EMT-related factors (TWIST1, SNAIL, SLUG, VIM) and invasion and metastasis-related genes (HER2, CXCR4, uPAR) in CTC-enriched blood fractions from N- and N+ breast cancer patients. This evidence concerns the gene CXCR4 and breast cancer.