ERBB2 and breast carcinoma: Biologically, it appears that luminal B-like breast carcinomas show a broad spectrum of sensitivity to endocrine therapy, likely related to the type of up-stream signals (e.g., IGF1R, HER family members including HER2, fibroblast growth factor receptor, etc.)that converge on the PI3K/AKT/mTOR and RAS/MAPK pathways to activate down-stream cellular processes such as cellular proliferation, resistance to cell death, and metabolic reprogramming [54,55].