ESR1 and neoplasm: Our previous studies have shown that the combination of BSp and GTPs resulted in synergistic inhibition of cellular proliferation, ERα reactivation via regulation of DNMT1 and HDAC1 expression in the ERα (-) breast cancer cell lines MDA-MB-231 and MDA-MB-157, and also resulted in a significant inhibition of tumor development in an ER(-) xenograft mouse model [26].