Fig. 2. ZO-1 and ZO-2 are tyrosine phosphorylated in QL12-MDCK cells by Src. Immunoprecipitations of the indicated TJ proteins were performed as described in the Materials and Methods followed by western blotting with 4G10 antibody. Identical amounts of lysate from QL12-MDCK cells +/–dox for 72 hours were used for each precipitation. Immunoprecipitations were repeated from cells cultured in PP2 (10 µM) or genistein (2 µM), which were added to the medium at the time of medium change to –dox. The intensity of the phosphotyrosine (pTyr) band (arrows) in each condition is normalized to the amount of protein in the precipitate. This fraction was divided by the fraction of pTyr detected in +dox cells with no inhibitor condition. Bar graphs on the right summarize the results from three experiments. (A) ZO-1; (B) ZO-2; (C) occludin; and (D) ZO-1 in G12-MDCK +/–dox. ^*P<0.05.