Its clinical relevance is further illustrated by the fact that TBCP-1 tumours and metastases maintain expression of HER2 and response to neratinib in vivo (evidenced by inhibition of HER2 signalling, tumour growth and metastasis) (Figs. 5 and 6) and metastasise to multiple organs commonly colonised by human HER2+ve breast cancer, including the brain (Fig. 2). This evidence concerns the gene ERBB2 and breast carcinoma.