Overexpression of GPx2 in the HER2-amplified JIMT1 cell line, which is GPx2 negative and brain-metastatic [34], suppressed mammary tumour growth (Fig. S6A, B), resulting in benign tumours with decreased VIM and increased E-CAD levels relative to control tumours (Fig. S6C). The gene discussed is GPX2; the disease is benign neoplasm.