FIGURE 1.

Tyrosine phosphorylation of Dbl. Anti-Dbl immunoprecipitates from transfected COS7 cells (A) or whole mouse brains (B) were immunoblotted (IB) with anti-phosphotyrosine (PY) antibodies. C, regulation of Dbl phosphorylation by serum. Serum-starved Dbl-transfected COS7 cells were stimulated with 10% FBS for the indicated duration, and tyrosine phosphorylation was examined as described in A. D, regulation of Dbl phosphorylation by EGF receptor and Src family kinases. Dbl-transfected EGFR expressing and parental CHO cells were starved, stimulated with EGF (50 nm), and treated with 1 or 10 μm Iressa or 1 or 10 μm PP2. Starvation and stimulation conditions are as described under “Materials and Methods.” All blots are representative of at least three independent experiments.