(A) Both β-catenin overexpression and LiCl significantly inhibited the SCN5a promoter activity (p<0.01), compared to the control groups, respectively. (B) Luciferase promoter assays revealed that β-catenin significantly inhibited SCN5a promoter activity in a concentration-dependent manner (p<0.01). (C) Knockdown of TCF4 by 100 nM SiRNA did not significantly affect the activity of SCN5a promoter, compared to the 100 nM scramble SiRNA group. (D) In the presence of β-catenin, knockdown of TCF4 by SiRNA significantly increased the SCN5a promoter activity (p<0.01), compared to the β-catenin and scramble SiRNA co-transfection group. **p<0.01; Ctl: control; n=3 batches of HeLa cells from 3 independent experiments carried on separate occasions for each group.