It is also possible that, when gene alterations occur in breast cancer, high proliferation rates are found irrespective of the presence of invasion and that other molecular alterations are involved in the development of breast cancer [35], Accordingly, the degree of differentiation does not contribute to the increase of the expression of both markers, though it may reflect the possible role of other pathways by which the tumor is advancing independently from the increase in signaling pathways of both HER2/neu and p53 genes. The gene discussed is ERBB2; the disease is breast carcinoma.