Isoflavone metabolites and their in vitro dual functions: they can act as an estrogenic agonist or antagonist depending on the estrogen concentration - Hwang, C S; Kwak, H S; Lim, H J; Lee, S H; Kang, Y S; Choe, T B; Hur, H G; Han, K O (J Steroid Biochem Mol Biol, 2006)