FIGURE 3.

Binding of hERα to DNA or Sp1 are dispensable for estrogen-mediated hSlo1 transcription. A, promoter activation assay of 2.5- or 5-kb constructs in HeLa cells cotransfected with empty vector (control), or with wild type hERα, or DBDM-hERα. Samples were stimulated with 1 nm estrogen (light gray bars) or with vehicle (dark gray bars) (n = 3). Values were normalized to estrogen-induced activity of hERα and 2.5 kb hSlo1 promoter expressing cells. * and **, significantly different from each other. B, RT-PCR analysis of HeLa cells cotransfected (+) or not (−) with siRNA directed against Sp1. GAPDH amplification is shown as control. C, cells expressing hERα and 2.5-kb or 5-kb constructs were cotransfected or not (control) with Sp1 siRNA and stimulated with vehicle (zero estrogen) or with estrogen (0.1 and 1 nm) (n = 3). *, significantly different from zero estrogen (vehicle).