FIG. 4.

Tyrosine phosphorylation of Gab3 in response to activation by various ligand-receptor systems. (A) BaF3 cells expressing the Flt3 receptor were stimulated with FL for the times indicated and the endogenous Gab3 or Gab2 protein was immunoprecipitated from aliquots of the cell lysate with antibody specific to each protein. After gel electrophoresis and transfer to nitrocellulose, the filters were immunoblotted with antibody to either phosphotyrosine (IB: αPY), Gab2 (IB: αGab2), or Gab3 (IB: αGab3). (B) BaF3 cells were stimulated with IL-3 and the tyrosine phosphorylation of Gab3 and Gab2 was tested as described above.