BRCA1 and breast cancer: We have directly demonstrated using human breast cancer cell lines, primary cultures from Brca1-deleted mouse mammary tumours and cultures from human BRCA1-null patient-derived breast cancer xenografts that BRCA1 loss results in activation of LYN and downstream pathways, including the AKT pathway, and confers a growth and survival advantage to mammary tumour cells (Tornillo et al., 2018).