Figure 1. Expression and transcriptional activity of p⁶⁷⁵-β-catenin in Pkhd1^del4/del4 cholangiocytes.

A) Representative Western blot and quantitative analysis showing a significantly higher expression of p⁶⁷⁵-β-catenin in Pkhd1^del4/del4 compared WT and PC-KO cholangiocytes both at baseline (C) and after treatment with forskolin (Forsk). The PKA inhibitor (PKI) significantly reduced the expression of p⁶⁷⁵-β-catenin (n=4). B) WT and cystic cholangiocytes were transfected with a TCF/LEF Top Flash reporter or its mutant, Fop Flash. Luciferase activity was normalized to Renilla luciferase activity. Transcriptional activity of β-catenin was higher in Pkhd1^del4/del4 compared to WT and PC-KO cholangiocytes, was increased by forskolin, and was inhibited by PKI and by quercetin (Querc), (n=6). (*p<0.05 vs WT and PC-KO untreated cells; ^{^}p<0.01 vs controls; ^●p<0.01 vs Forsk; ^op<0.05 vs controls).