The only term significantly enriched for HER2 tumours was the ErbB signalling pathway, whereas the PyMT tumours were characterised by processes involving PI3K signalling, including type 2 diabetes mellitus, the FcεRI signalling pathway, acute myeloid leukaemia, Fcγ receptor–mediated phagocytosis and the neurotrophin signalling pathway. The gene discussed is PIK3CA; the disease is type 2 diabetes mellitus.