BRCA1 and neoplasm: Therefore, whereas our previous findings established that basal mammary cells were more sensitive than luminal cells to loss of Brca1/2, Pten and p53 (Melchor et al., 2014; Molyneux et al., 2010), here we demonstrate that luminal cells are more sensitive to activation of the NeuKI allele and that the basal cell population is less sensitive to the tumour-promoting activity of this allele.