Heatmap of a cancer dataset  clustered using the normal gene signature. This signature identifies a distinct cluster of 38 estrogen receptor (ER)/progesterone receptor (PR) negative, HER2 negative samples corresponding to the basal breast cancer subtype . Elevated expression of normal stroma-specific genes appears in a portion of the lumenal and HER2 positive tumors, although this expression does not correlate with the known molecular subtypes of breast cancer.
Finak et al. Breast Cancer Research 2006 8:R58 doi:10.1186/bcr1608