Importantly, there is functional crosstalk between the estrogen receptor and other steroid hormone receptors, such as the progesterone receptor (PR), glucocorticoid receptor (GR), and androgen receptor (AR) in breast cancer cells [79,80,81,82,83,84,85], as well as other cancer cell types, like endometrial [86,87]. This evidence concerns the gene ESR1 and breast carcinoma.