Fig. 1.
Expression and autophosphorylation of IGF-IR.
Cells were serum-starved for 18 hours and were untreated (−) or treated (+) with IGF-I. Lysates from 1 × 107 cells were incubated with anti–IGF-IR antibody, and immunoprecipitates were prepared and analyzed as described in “Materials and methods.” Blots were probed with antibody to the IGF-IR (A) or phosphotyrosine (B).