Similarly, 26/56 (46.4%) BrM mice and all (n = 70) BrMSB mice developed mammary tumours during the same period of time, with a faster acceleration of tumourigenesis in BrMSB75 than in BrMSB40 strains (Supplementary Fig. 1b, c; Supplementary Data 1). The gene discussed is SMARCA2; the disease is breast cancer.