ESR1 and breast cancer: A study of the effects on proliferation and metastasis of MCF-7 human BC cells expressing estrogen receptors (ER) [41] found that treatment with BP1 (10− 5–10− 7 M) and NP (10− 6–10− 7 M) promoted proliferation of MCF-7 cells similarly to the positive control 17-beta-estradiol (E2).