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]. The gene discussed is MAPK3; the disease is breast carcinoma.