The alterations in MCF-7 cells were compared to T47D (human breast ductal carcinoma, estrogen receptor low ERα(+)/ERβ(+) ratio) [24], MB-231 cells (human breast adenocarcinoma, ERα(-)) and doxorubicin-resistant MCF-7/ADR cell lines. The gene discussed is ESR1; the disease is breast ductal adenocarcinoma.