Histological analyses of tumours showed that, while Mettl1-expressing tumours were invasive and consisted of undifferentiated cells, tumours from Pten-KO/Mettl1 +/- and Pten-KO/Mettl1flox/flox mice were encapsulated and consisted of differentiated luminal cells with low proliferative potential (Supplementary Fig. S9D, S9E, S9G), suggesting that Mettl1 is required for tumorigenesis. The gene discussed is METTL1; the disease is neoplasm.