ESR1 and breast carcinoma: Following genistein treatment, MCF-7 breast cancer cells (with high ERα/ERβ ratio) and MDA-MB-231 (ER negative) have shown an increased proliferation rate, while in T47D breast cancer cells (with low ERα/ER ratio), the same treatment produced cell cycle arrest, improved mitochondrial functionality [32] and decreased the oxidative stress [33].