The hypermethylation defect observed among breast cancer cell lines is associated with a characteristic gene expression signature that reflects methylation-dependent silencing of a panel of epigenetic biomarker genes (including CDH1, CEACAM6, CST6, ESR1, GNA11, MUC1, MYB, SCNN1A and TFF3) (10). The gene discussed is ESR1; the disease is breast carcinoma.