SMC3 knockdown decreases ERα gene expression and protein level. (A) MCF7 cells were transfected with control or SMC3 siRNA. After cell adhesion, growth medium was changed to hormone-deprived 5% CSS medium. Total mRNA was harvested 12, 24, 36 and 48 h after transfection. SMC3 and ESR1 expression was normalized to 28S ribosomal mRNA, graphed relative to the control sample and expressed as relative mRNA expression; mean values + SD, n = 2. (B) MCF7 cells were transfected with control, SMC3 or MED12 siRNAs and grown overnight. Cells were switched to hormone-free medium for 32 hours before harvesting whole protein extracts and analysis by Western blot for MED12, SMC3, ERα and HSC70 protein levels. (C) MCF7 cells were transfected as in (A). Whole protein extracts were analyzed via Western blot with specific antibodies for SMC3 and ERα. β-Actin and HSC70 are shown as loading controls.