A metabolite of equine estrogens, 4 hydroxyequilenin, induces DNA damage and apoptosis in breast cancer cell lines. - Chen,Y.; Liu,X.; Pisha,E.; Constantinou,A.I.; Hua,Y.; Shen,L.; van Breemen,R.B.; Elguindi,E.C.; Blond,S.Y.; Zhang,F.; Bolton,J.L. (Chem Res Toxicol, 2000)