Several drugs have been developed to target the ERα in the context of breast cancer but, while these drugs inhibit the ERα in the breast, they were found to stimulate its activity in the CNS (Halbreich and Kahn, 2000; Littleton-Kearney et al., 2002; Miller, 2002; Veenman, 2020). The gene discussed is ESR1; the disease is breast carcinoma.