Downregulation of β-catenin/TCF-driven transcription on knockdown of β-catenin. (a) HeLaT-β-catenin-RNAi cells were transfected with TOPFLASH or FOPFLASH luciferase reporter construct. After 3 days with or without DOX treatment, luciferase reporter gene expression was determined. The pRL-TK Renilla luciferase reporter construct was co-transfected in each sample to normalize transfection efficiency. The activity of the reporter luciferase is expressed relative to the activity in control cells, which is defined as 1.0. All experiments were performed in triplicate and are expressed as means and SD. (b) Relative expression levels of known β-catenin/TCF target genes in the HeLaT-β-catenin-RNAi cells following treatment with DOX, as measured by semi-quantitative RT-PCR. β-actin expression is used as a control.