In addition to the previously reported feature that ERs expressed in LTED cells display ligand-independent activity [2,3,4,5,6], we recently reported that LTED cells express very low levels of G protein-coupled estrogen receptor 1 (GPER1, formerly known as GPR30), such that its expression is comparable to that of GPER1 produced by human breast cancer MDA-MB-231 cells, a GPER1-negative (or very low), and an ER-negative cell line [6]. Here, ESR1 is linked to breast cancer.