The ESRs (Estrogen Receptors) are ligand-dependent transcription factors and are important Nuclear Hormone Receptors that act as regulators of cell growth, differentiation and malignant transformation. Transcriptional activation by ESRs is accomplished through specific and general cofactor complexes that assemble with the receptor at target promoters to regulate transcription. The chief ligand for ESR is the ovarian steroid hormone Estrogen, which has a primary role in the establishment and maintenance of reproductive function (Ref.1). Naturally occurring forms of Estrogen are Estradiol, Estriol, and Estrone. Estradiol is the most commonly occurring form of Estrogen in non-pregnant women. Binding of Estrogen to the ESR promotes a conformational change in the receptor and the formation of a surface for protein-protein contacts between receptor domains [...]