However, trastuzumab causes a similar decrease in proliferation in the two HER2+/pHER2Y877+ BC cell lines BT-474 and SKBR3 (p<0.0001 for both), as there is no difference between either the cell lines (p = 0.11) or the slopes (p = 0.99) (Fig 5B and 5C). Here, ERBB2 is linked to breast cancer.