It has been also proven in many studies that E2, the main estrogen in serum before menopause, inhibits the NF-κB pathway [24]; however, the role of E1, the major estrogen in the bloodstream after menopause and whose levels increase with obesity as it does the risk of developing ER+ cancers, has not been explored until date. This evidence concerns the gene NFKB1 and obesity due to melanocortin 4 receptor deficiency.