Fig. 4. TCF/Lef-dependent induction of predicted ß-catenin targets. (A) Adenoviruses expressing wild-type (Ad-CTNNB_WT) or stabilized (Ad-CTNNB_S37A) ß-catenin induce TCF/Lef-dependent Topflash reporter activity in human embryonic kidney (HEK)293 cells at moderate and high levels, respectively. The effect of Ad-CTNNB_S37A is effectively blocked by co-infection of Ad-DN-TCF. (B) As determined by real-time RT-PCR, Ad-CTNNB_S37A significantly induces expression of 10/15 (66%) predicted TCF/Lef target genes in metanephric mesenchymes after 14 hours of culture when compared with Ad-GFP only. This induction is consistently blocked by co-infection of Ad-CTNNB_S37A and Ad-DN-TCF (n=3, values are represented as mean±s.e.m.). Expression levels under control conditions (Ad-GFP only) were set to 1. Conversely, stabilization of ß-catenin in metanephric mesenchyme does not induce expression of genes associated with epithelial differentiation that lack predicted TCF/Lef sites (Frzb, Lama1, Tcfap2b), or of Myc, a TCF/Lef target gene in other cell types, which is not significantly regulated during epithelial differentiation (Controls). ^*, Significantly upregulated versus Ad-GFP only (P<0.05); #, significantly downregulated versus Ad-CTNNB_S37A+Ad-GFP (P<0.05).