Fig. 2.

Effects of Sp3 on small-conductance calcium-activated potassium channel 3 (SK3) promoter activation in the presence and absence of Sp1. Drosophila Schneider's line 2 cells were cotransfected with an SK3 promoter-driven luciferase gene and 1 μg of the Pac vector (control), Sp3si, and Sp3 long isoform (Sp3li) (A) or Sp1 plus Sp3si at various concentrations (B) as indicated. Bioluminescence was quantified, revealing that Sp3si and Sp3li alone can reduce SK3 promoter activation (n = 4–6). Means ± SE. A: *P < 0.05 vs. Pac. B: Sp3si dose-dependently reduced Sp1 activation of the SK3 promoter (n = 6). Means ± SE. *P < 0.05 vs. Sp1.