ERBB2 and breast cancer: Consequently, we targeted ERBB2 (HER2), which is amplified ( ~ 50 copies) in the breast cancer cell line BT-474, and MYC, which is amplified ( > 400 copies as ecDNA)123,124 in non-small cell lung cancer cell line NCI-H2170 and the colorectal cancer cell line NCI-H716 (Fig. 6A, B).