To validate the association of increased IFN signaling with HER2 amplification, we also analyzed the ISG gene expression in a large cohort of HER2-positive breast cancer invasive carcinoma samples from The Cancer Genome Atlas (TCGA, 2015 Cell) [18] and found a significantly higher ISG score in 108 HER2-positive IDC samples compared to 644 HER2-negative IDC samples (supplementary Figure 8). This evidence concerns the gene IFNA1 and breast cancer.