Based on the whole transcriptomes of the 23 BRCA1-deficient mammary tumors, four subgroups are identified via hierarchal clustering, and termed as mesenchymal like, luminal like I and II (Lum I and Lum II), and mixed types respectively because of their differential expression patterns of mammary basal/luminal lineage markers and epithelial/mesenchymal cell markers (Figure 2A-B). This evidence concerns the gene BRCA1 and breast cancer.