ERBB2 and breast cancer: The expression of IGF1R, a 95‐kDa transmembrane tyrosine kinase receptor, was initially investigated in MDA‐MB‐231, MDA‐MB‐453, MCF7, and BT474 cell lines that correspond to the basal, HER2‐positive, luminal A, and luminal B breast cancer subtypes, respectively (Neve et al., 2006).