Cell motility was examined by the Boyden chamber assay. Cells that had migrated to the underside of the porous polycarbonate membrane were quantified under a phase-contrast microscope. Representative images are shown in (A) (Original magnification 40X). B) Cell motility was significantly higher in Pkhd1del4/del4 with respect to WT and PC-KO cholangiocytes, was cAMP/PKA-dependent, due to the boosting effect of forskolin (F) and the inhibitory effect of PKI, and was inhibited by the Rac-1 inhibitor, NSC 23766, by the β-catenin inhibitor, quercetin (Querc), and by β-catenin silencing (siRNA). (n=7; *p<0.05 vs WT and PC-KO untreated cells; ^p<0.01 vs controls; ●p<0.01 vs Forsk; ○p<0.05 vs controls).