ESR1 and neoplasm: Importantly, the existence of selective ERβ agonists [80,84,85,87], summarized in Section 3.3, allows to enhance the tumor suppressor effect guided by the receptor in vitro, and, once the problems with ERβ detection in human tissues is solved, they could be successfully used to activate ERβ in TNBC patients, without stimulating the pro-proliferative program driven by ERα in normal human cells.