In these experiments two different antibodies [phospho-specific anti-Stat3 antibody (35), and phospho-specific anti-caveolin-1 antibody], both cross-reactive to phosphorylated GRP-75 were used. A, Anti-phospho-caveolin-1 antibody immunoblot of samples immunoprecipitated with phospho-specific anti-Stat3 antibody. Serum starved cells were left untreated, or treated with Ang II for 15 min (100 nM). Cell lysates were prepared and immunoprecipitated (IP) with phospho-specific anti-Stat3 antibody, immunocomplexes were run on an 8% SDS-polyacrylamide gel and probed with phospho-specific anti-caveolin-1 antibody. B, The samples representing A were immunoprecipitated with phospho-specific anti-caveolin-1 antibody, immunocomplexes were run on an 8% SDS-polyacrylamide gel and probed with phospho-specific anti-Stat3 antibody. These blots are representative of three independent experiments. IgH, Immunoglobulin heavy chain. CR= cross reactive.