ERBB2 and breast cancer: As H2170 is a HER2-amplified (HER2+) cell line, we further studied this binding between HER2 and METN375S in HER2-non-amplified isogenic Calu-1 cells (Supplementary Fig. 6A–C), as well as in breast cancer cell lines that included SKBR3 (HER2-amplified) and MCF7 (HER2-non-amplified) (Supplementary Fig. 6D, E) to eliminate the possibility that the interaction is attributable to relative abundance of HER2 receptors.