Two mammary tumour cell lines derived from Brca1f/f/p53±/BLG-Cre mammary tumours (Molyneux et al., 2010), Brca1.3 and Brca1.1516, express low levels of Sox11 in comparison to C2C12, an immortalised mouse myoblast cell line (Fig. S1B). This evidence concerns the gene BRCA1 and breast cancer.