The aim of the present work was to study mitochondrial functionality and invasiveness, analyzing mitochondrial biogenesis and dynamics processes, as well as oxidative stress and inflammatory status and motility, in cell lines with different estrogen receptors ratio, exposed to a treatment consisting of 17β-estradiol, leptin, IL-6, and TNFα simulating circulating hormonal conditions in a postmenopausal obese woman [31,32,33] Likewise, the expression of the main antioxidant genes and genes related to inflammation and mitochondrial functionality in breast cancer tumors have been studied. This evidence concerns the gene ESR1 and breast cancer.