Other than histological subtypes, gene expression profiling has classified breast cancer into different molecular subtypes, i.e., receptor-positive (Luminal A, Luminal B, Normal like, and HER-2 (Human epidermal growth factor receptor) 2 positive ) and receptor-negative (TNBC (Triple negative breast cancer)) or Basal like) (Figure 1) [4–6]. Here, ERBB2 is linked to breast cancer.