ERBB2 and breast cancer: Next, we estimated the sensitivity of BC5, BrCCh1, and BN1 breast cells to various chemotherapeutic agents: doxorubicin, cisplatin, tamoxifen, anastrozole, and the mTOR-inhibitor afinitor (everolimus), which is used for treatment of advanced hormone receptor-positive, HER2-negative breast cancer [23].