Clone 19 exhibits doxycycline-induced downregulation of the Wnt hyperactivation by butyrate. (A) Cells were transfected with TOPFlash or FOPFlash reporters and pRLTK (to control for transfection efficiency) and expression of DN-Tcf4 was induced by treatment with 4 μg/ml doxycycline; cells were also treated or not treated with 5 mM butyrate (NaB), both agents (DoxyNaB); control (Ctl) cells were not treated with either agent. After 17 hr of butyrate treatment, Wnt transcriptional activity was measured via luciferase assays. T/F represents the ratio of expression of TOPFlash (wild-type Wnt-responsive promoter) compared to FOPFlash (mutant promoter), measuring overall canonical Wnt activity. (B) Data from (A) represented by the fold-upregulation of Wnt activity in the presence (DoxyNaB/Doxy) or absence (NaB/Ctl) of doxycycline. (A) and (B) show data from four independent experiments. Bars, SDs. * = statistical significance.