erb-79 erb-79 erb-79 is a synthetic estrogen and a selective agonist of the erβ. it is a racemic mixture, with the active enantiomer being erb-26. erb-79 shows more than 484-fold selectivity for transactivation of the erβ over the erα. its ec50 value for the erβ is 0.448 nm (14.52% of the potency of estradiol) and for the erα is 79 nm (0.03% of the potency of estradiol). it has no antagonistic activity at either receptor. erb-79 is active in preclinical models of arthritis. the chemical structure of erb-79 does not appear to have been disclosed. erb-79clinical datadrug classestrogen; selective erβ agonistidentifierscas number1807969-57-8