CreLox system enables switching on activated β-catenin. (A) Schematics of DNA constructs used in this study. Grey boxes indicate promoters; red arrowheads indicate loxP sites. ABC, Activated β-catenin. (B,C) Switching in Tg(fabp10a:Cre) (HepCre),Tg(fabp10a:flox-pt-β-cat) (FloxABC) and Tg(fabp10a:Cre); Tg(fabp10a:flox-pt-β-cat) (HepCre+FloxABC) larvae imaged at 5 dpf for BFP expression, detected by immunofluorescence using an anti-GFP antibody. Successful switching is indicated by loss of BFP expression. (B) Representative images. Livers are outlined. Scale bars: 50 µm. (C) Scatter plot with bar graph quantifying switching in terms of mean intensity of GFP fluorescence, ±standard deviation (s.d.). P-values derived using Sidak's multiple comparisons test following ordinary one-way ANOVA. N values are shown above x axis. Experiment was performed three times, with similar results each time, and representative results are shown. (D,E) Wnt reporter activity in Tg(fabp10a:Cre) (HepCre),Tg(fabp10a:flox-pt-β-cat) (FloxABC) and Tg(fabp10a:Cre); Tg(fabp10a:flox-pt-β-cat) (HepCre+FloxABC) siblings imaged at 5 dpf alongside Tg(fabp10a:pt-β-cat) (HepABC) and non-transgenic siblings (NonTg). All zebrafish contain 7xTCF-Xla.Siam:mCherry transgene for visualization of Wnt reporter activity by immunofluorescence. (D) Representative images of Wnt reporter activity (7xTCF-Xla.Siam:mCherry). Livers are outlined. Scale bars: 50 µm. (E) Stacked bar graphs showing percent of zebrafish with absent (A), low (L, involving <10% of hepatocytes) or high (H, involving >10% of hepatocytes) Wnt reporter activity. P-values derived using Fisher's exact test. N values are shown above x axis. Three experiments were pooled.