Structures of diverse endocrine disruptors that modulate estrogen signaling. AHR, aryl hydrocarbon receptor; HPTE, 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane; PCB, polychlorinated biphenyl; PCDD, polychlorinated dibenzo-p-dioxin; PCDF, polychlorinated dibenzofuran; TCDD, 2,3,7,8-tetrachlorodibenzo-p-dioxin.