Assessment of the selection coefficients of ENU-induced mutations using the dNdScv method16 confirmed that nonsense mutations in Apc and missense mutations in Ctnnb1 were positively selected (q values close to zero; Fig. 1f, Supplementary Table 4 and Supplementary Table 5), identifying these mutations as tumour drivers. The gene discussed is CTNNB1; the disease is neoplasm.