In 2000, Perou and co-workers indentified five molecular subgroups of breast cancers (luminal A, luminal B, normal breast-like, Her2 positive or basal-like) by use of cDNA microarray and un-supervised cluster analysis [20], and several studies have since addressed the immunohistochemical surrogates to these subgroups [21]. Here, ERBB2 is linked to breast carcinoma.