ERBB2 and breast cancer: In contrast, less aggressive BC cell lines such as MCF-7 (Luminal-HER2 negative type), BT-474 (Luminal-HER2 positive type), or SK-BR-3 (HER2 positive type) showed minimal to no invasiveness (0.00, 0.00%, or 0.14% ± 0.02, respectively) (Fig. 1a-b).