Figure 2

Gene expression patterns associated with tumorigenic cells are manifested in normal breast samples with positive staining for the stem-cell markers CD44⁺/CD49f⁺/CD133/2⁺. On the basis of gene expression profiling, normal breast samples were each assigned a score for similarity to a previously defined gene signature of tumorigenic cells. CD44⁺CD49f⁺CD133/2⁺ samples scored highly for the gene signature (P <0.001, Wilcoxon rank sum test): black bar, normal adjacent tissue. Analysis of epidemiologic factors revealed associations between stem cell presence and triple-negative tumor subtype (P = 0.001), breastfeeding (P = 0.04) and recurrence (P = 0.01). ^*P <0.05.