Figure 5.
Effect of echistatin on tyrosine phosphorylation of IGF-I receptor after IGF-I stimulation. Subconfluent SMCs were incubated without echistatin (lanes 1 and 2) or with echistatin at 10−8 M (lane 3) and 10−7 M (lane 4) for 12 h in serum-free DMEM-H. The cells were exposed to no IGF-I (lane 1) or 100 ng/ml IGF-I (lanes 2–4) for 10 min. The cells were lysed, and the lysate was immunoprecipitated by using an anti-IGF-I receptor β subunit antiserum. The precipitated proteins were separated by 7.5% SDS/PAGE and transferred to a PVDF membrane. The membrane was blotted with an antibody against phosphotyrosine (A) or an antibody against IGF-I receptor β subunit (B).