Breast cancer cell lines provide an interesting model to study relations between AQP3 and the EGFR signaling pathway, as MCF7 are positive for hormone receptors (ER and PR), SkBr3 are positive for human epidermal receptor 2 (HER2), and SUM159PT are negative for both hormone receptors and HER2. The gene discussed is EGFR; the disease is breast carcinoma.