FIG. 9.

K-ras transfection of IEC epithelial cells induces plakoglobin phosphorylation and upregulates binding to α-catenin. (A and C) Three hundred micrograms of whole-cell extracts from control and K-ras IEC18 cells were immunoprecipitated (IP) with anti-plakoglobin (A) or anti-α-catenin (B) and followed by immunoblotting with the indicated MAbs. (B and D) IEC18 and IEC18 K-ras cells were transfected with 5 μg of pcDNA3.1His-plakoglobin (wild-type [WT] or the indicated mutants). His-tagged plakoglobin was purified by chromatography on nickel-agarose, and the level of tyrosine phosphorylation (B) or α-catenin association (D) was analyzed by Western blotting (WB) with specific antibodies. The membranes were reprobed for plakoglobin to check that similar levels of expression were obtained.