BRCA1 and breast cancer: Lim E et al. [166] classified normal breast epithelial cells from BRCA1 mutation carriers into three types: basal, mature luminal, and luminal progenitor cells based on flow cytometry, and the Basal-like subtype of breast cancer showed high expression of the luminal progenitor cells gene signature, while the Luminal A and Luminal B subtypes exhibited high expression of the mature luminal cells gene signature, suggesting variability in the origins of different molecular subtypes of breast cancer.