They used hierarchical modeling to examine clustering in relation to breast cancer subtypes, and found that clusters separated into 3 groups, one primarily luminal A and another basal-like (negative for ER, PR and HER, and over-expression of EGFR and CK5/6), with a third non-specific group that included normal samples, similar to our findings of separation between normal and tumor and by ER status. The gene discussed is ESR1; the disease is breast carcinoma.