Fig. 4. Quantitative analysis of the effect of cytochalasin D on the interaction between cortactin and dynamin 2. (A) NIH3T3 cells were treated with 10 µM cytochalasin D or DMSO for 0, 30, 60 or 90 minutes, followed by transferrin treatment for addition 10 minutes. The treated cells were lysed and immunoprecipitated with dynamin antibody. The immune complex was subjected to SDS-PAGE and immunoblot assay using cortactin antibody. To measure dynamin, filters were stripped and reblotted with dynamin 2 antibody. In a parallel experiment, internalization of biotin-labeled transferrin was performed in cytochalasin D-treated cells. The internalized transferrin was detected by immunoblot analysis with biotin antibody. (B) Quantification of the interaction between cortactin and dynamin was performed based on two independent experiments and the mean±s.d. is shown.