TABLE 1.

RLAs of different estrogens to ERα and ERβ

The RLA of each ligand was calculated as the ratio of IC₅₀ of 17β-E₂ and IC₅₀ of competitor, multiplied by 100. Each value is the mean ± S.D. of measurements obtained from three independent experiments. The ratios of RLA for ERβ/ERα are shown. A ratio greater than 1 indicates higher affinity for ERβ, and a ratio less than 1 indicates higher affinity for ERα. Numbers in brackets ([100] or [1]) are the base values on which the RLA values are calculated. A value of 100 represents a K_d = 0.2 nm for ERα and 0.5 nm for ERβ (18).

Ligand name	RLA		RLA β/α
	ERα	ERβ
17β-E2	[100]	[100]	[1.0]
E1	4.5 ± 0.7	4.0 ± 1.0	0.89
E3	6.8 ± 0.7	11.6 ± 0.6	1.7
EE2	194 ± 22	151 ± 27	0.78
17α-E2	13.7 ± 1.6	5.3 ± 1.8	0.39
DES	290 ± 56	278 ± 54	0.96
DMS	22.2 ± 4.3	237 ± 28	10.7
Meso-Hex	314 ± 44	697 ± 74	2.2
dl-Hex	4.4 ± 0.3	60.3 ± 5.3	13.7
Equ	2.3 ± 0.2	3.2 ± 0.3	1.4
Eqn	0.35 ± 0.04	2.0 ± 0.3	5.7
Gen	0.06 ± 0.01	7.4 ± 0.5	123