A form of β-catenin that does not localise to the cell membrane shows low transcriptional activity.

<p>(A) Fluorescent microscopy of MDCK cells immunostained for transfected Flag-tagged β-catenin of wild type (WT) and various mutant forms as indicated. Exogenous β-catenin, detected by anti-Flag antibody, is localised to the cell membrane, except for the Y654E mutant, which shows cytoplasmic distribution. Scale bar, 20 µm. (B) Similar analyses as (A), with co-staining with E-cadherin (red) and nuclei (blue). Wild type β-catenin co-localises with E-cadherin, whereas Y654E does not. Scale bar, 20 µm. (C, D) TOPflash reporter assay of the β-catenin mutants in MDCK cells, without (C) or with (D) HGF in the medium. The fold activation was normalised against cells transfected with control DNA without HGF treatment. Transcriptional activation is similar amongst all the constructs with the exception of Y654E, which gives a much-reduced transcriptional readout (*<i>P</i><2×10⁻⁷ compared to other β-catenin constructs) in both conditions.