ERBB2 and breast carcinoma: We first selected a human primary mammary epithelial cell (HMEC) line and five cell lines derived from breast cancer subtypes with different levels of aggressiveness: T47D (luminal A, lowest aggressiveness), ZR7530 (luminal B), HCC1954 (HER2+), HCC70 (TNBC A), and BT549 (TNBC B, highest aggressiveness) cells.