Human HER2 was expressed on the EMT6-hHER2 cells at a level that was comparable to KPL-4 cells, a representative human HER2-positive (immunohistochemistry 3+ determined by Herceptest) cancer cell line [1, 24] and CT26.WT-hHER2 human HER2-expressing mouse cancer cell line [19] (Fig 1A). Here, ERBB2 is linked to cancer.