Fig. 6. Biochemical analysis of the degree of maturation of cell-cell contacts in T98G and U373MG cell lines. (A) Western blot analysis of the amount of LIN-7 and ß-catenin recovered in the TX-100-soluble (S) and TX-100-insoluble (I) fractions. T98G or U373MG glioblastoma cells grown to confluence were extracted in TX-100. Equivalent volumes of the soluble or insoluble fractions were separated by 10% SDS-PAGE and immunostained using the indicated antibodies. (B) Total P-tyr content in T98G and U373MG cells. 5x10⁵ cells were plated, cultured for 72 hours and extracted in lysis buffer containing 0.02% SDS and 100 µM pervanadate. Five percent of the cell lysate used in the immunoprecipitation experiments was probed for P-tyr. (C,D) Tyrosine phosphorylation of - and ß-catenin. The cell lysates were immunoprecipitated with anti--(C) or anti-ß-catenin (D) antibodies and probed for P-tyr. To confirm similar protein loading, 10% of the immunoprecipitates were probed for - (C) or ß-catenin (D). Molecular weight standards expressed in kDa are indicated on the left.