In contrast, deletion of the classical gatekeeper tumour suppressor gene phosphatase and tensin homologue (Pten), which dephosphorylates phosphatidylinositol-(3,4,5)-trisphosphate and acts as a negative regulator of the protein kinase B signalling pathway, leads to invasive adenocarcinoma with a reported cumulative incidence of 100% within 29 weeks of age [36]. The gene discussed is PTEN; the disease is neoplasm.