In breast cancer, molecular profiling of patient tumors led to the identification of transcriptional breast cancer subtypes, categorized as Basal, Luminal A, Luminal B, Her2+, Claudin-low and Normal-like [13,14,15,16], with further sub-classification of the triple negative breast cancers (TNBC) into 10 distinct groups [17]. Here, ERBB2 is linked to breast cancer.