In the cell experiment, they used three kinds of breast cancer cells (BT-474: HER2, EpCAM expressed; MCF-7: HER2-negative, EpCAM-positive: UACC-812: HER2-positive, EpCAM-negative), and a normal breast epithelial cell (MCF-10: HER2, EpCAM-negative). Here, ERBB2 is linked to breast cancer.