Eight LCLs homozygous for variant genotypes for the ZNF423 SNPs; seven cell lines with heterozygous genotypes; and eight cell lines homozygous for WT sequences at those SNPs, all stably transfected with ERα as described previously, were used in these studies. These stably transfected LCLs were cultured in RPMI media containing 15% (vol/vol) FBS with 200 μg/ml Zeocin. Prior to E2 treatment, 2×107 cells from each cell line were cultured for 24 h in RPMI media containing 5% (vol/vol) charcoal stripped FBS with 200 μg/ml Zeocin, followed by culture in the same medium without FBS for another 24 h. All cells were then cultured for 24 h in 6-well plates, with RPMI 1640 media that contained 0, 0.00001, 0.0001, 0.001, 0.01, 0.1, 1.0 and 10 nM E2. 4-hydroxytamoxifen (Sigma-Aldrich, St. Louis, MO) or raloxifene (Sigma-Aldrich) were then added to the same medium containing 0.01 nM E2 at final 4-hydroxytamoxifen concentrations of 10−8, 10−7, 10−6 and 10−5 μM, or raloxifene concentrations of 10−6 to 10−3 μM, and the cells were cultured for an additional 24 h. Total RNA was isolated from the cells with the RNeasy mini kit (Qiagen, Valencia, CA). Two hundred ng of total RNA was then used to perform qRT-PCR with ZNF423, BRCA1, and ERα primers. ZNF423 and BRCA1 expression levels were normalized on the basis of ERα expression in each cell line.