E2 binds to the nuclear estrogen receptors (ERs) ERα and ERβ, and the formed complexes promote the transcription of genes containing estrogen response element sequences, which also may lead to the development of several types of estrogen-responsive cancers [158,161] including breast [162], endometrial [163], and ovarian cancers [164]. The gene discussed is ESR1; the disease is ovarian carcinoma.