Effect of dominant-negative SYK and PP1 on tyrosine phosphorylation of CBL in response to stimulation with IgG-sensitized sRBCs.

(A-B) Western blot analysis of CBL immunoprecipitates to assay the phosphorylation of CBL following treatment of IgG-sensitized sRBCs in J774A.1 cells expressed by dominant-negative SYK, treated with Src family kinase inhibitor, PP1 (10 μM). J774A.1 lysates prepared from resting cells or cells stimulated with sensitized sRBCs for 5 minutes were immunoprecipitated with polyclonal anti-CBL antibody and immunoblotted with monoclonal antiphosphotyrosine antibody to determine phosphorylation of CBL or immunoblotted with polyclonal anti-CBL antibody to determine total protein amounts of CBL under the same nitrocellulose membrane.