Indeed, ERβ was detected in mitochondria of rat (uterus, ovarian, hippocampus, and neuronal cells) and human (cardiomyocytes, sperm, periodontal ligament, and cultured lens epithelial cells) tissues, altogether with BC (MCF7), hepatocarcinoma (HepG2), and osteosarcoma (SaOS-2) cell lines [154]. This evidence concerns the gene ESR2 and breast cancer.