New potential prognostic biomarkers of breast cancer metastasis are continuously being uncovered, which include uPA/PAI1, ER, PR, HER2/ErbB2, circulating tumor cells, the presence of epithelial cells in the bone marrow [12, 16], E-cadherin [17] and, more recently, nucleobindin-2 [18]. The gene discussed is ERBB2; the disease is breast cancer.