Table 1.

Relative binding affinities of ligands to full-length ERα or ERβ

	RBA
Ligand	ERα	ERβ
17β-Estradiol	100	100
4-Hydroxytamoxifen	36	43
Raloxifene	34	76
GW-5638	5	8
STX	4.3E-6	9.0E-6

Relative binding affinities (RBA) are expressed as a percentage of the potency of 17β-estradiol. Under the experimental conditions described in Materials and Methods, 17β-estradiol was found to have an IC₅₀ of 5 nm for ERα and 3 nm for ERβ.