Figure 5.

Gab1 and Sos1 associate with Grb2 in a same complex. (A) Quiescent NIH 3T3 cells were unstimulated or stimulated with FGF1 and heparin (100 ng/ml and 5 μg/ml, respectively) for 5 min. The lysates were immunoprecipitated with Grb2 (i) or Sos1 (ii) antibodies and followed by SDS–PAGE and immunoblotting with Gab1, Sos1, or Grb2 antibodies. (B) The 293 cells were transfected with expression vectors for FGFR1, Sos1, and Gab1 as indicated. Equivalent amounts of total cell lysates were resolved by SDS–PAGE and immunoblotted with anti-FGFR1, Gab1, or Sos1 antibodies. Alternatively, the lysates were immunoprecipitated with anti-Grb2 and followed by SDS–PAGE and immunoblotting with anti-Sos1 or Grb2 antibodies.