Fig. 1. Preparation and characterization of the specific anti-phosphorylated-ß-catenin antibody. (A) A schematic representation of the ß-catenin molecule and the doubly phosphorylated peptide corresponding to its N-terminus that was used to prepare the antibody. Note the homology between ß-catenin and plakoglobin at this region. (B) An ELISA assay for determining the specificity of the antibody. Binding of the antibody to the doubly phosphorylated peptide was detected by a peroxidasebased reaction in the absence of a competitor (first lane on the left) or in the presence of increasing amounts (12.5 25, 50 and 100 µg/ml) of the indicated peptide competitors.