Estrogen 17β-estradiol and antiestrogen fulvestrant (ICI-182,780) induced a rapid but transient activation of Erk1/2 in ERα/ERβ-negative breast cancer cells SKBR3 that express GPR30 but not in GPR30 non-expressing MB-MDA231 cells [214]. This evidence concerns the gene ESR1 and breast carcinoma.