The ER–ligand complex thereafter translocates to the nucleus and henceforth interacts with the target gene of interest through either of the following two ways: Firstly, estrogen–receptor complex can bind to the specific DNA sequence within the estrogen response elements (ERE) of the target gene promoter and subsequently either activate or inhibit the transcription of these genes [33] and [34]. Secondly, estrogens modulate the expression of genes in absence of ERE with the help of various transcription factors like NF-κB [35], AP-1 [36], SP-1 [37] and GATA [38] etc. Estrogens modulate the activity of these transcription factors that in turn move into the nucleus, bind to the specific recognition sites at the promoter region of the target genes and thereby activate or inhibit their corresponding expression in the target cells.