To examine the role of BCL11A in mammary tumour development in vivo, we generated Bcl11a conditional knockout (cko) mice (referred to as flox/flox; Supplementary Fig. 6a), as germline deletion of Bcl11a causes neonatal lethality27 and crossed them to the inducible Rosa26-CreERT2. As a tumour model, we used the potent carcinogen DMBA (7,12-dimethylbenz(a)anthracene) in combination with medroxyprogesterone acetate (MPA) to promote TNBC-like tumours in the mouse28, 29. This evidence concerns the gene BCL11A and breast cancer.