Fig. 4. GEF activity of PLC-1 for dynamin-1 enhances dynamin-1-dependent endocytosis. (A-D) PC12 cells transfected with various PLC-1 constructs (A), siRNA to PLC1 (described in Materials and Methods, #1 and #2) (B), various dynamin-1 constructs (C) or the SH3 domains of PLC-1 and amphiphysin (D) were stimulated with EGF for the indicated times. Cell surface proteins were biotinylated as described in Materials and Methods (Lu et al., 2002). Biotinylated proteins were recovered using streptavidin, and the amount of EGFR recovered was assessed by immunoblotting with anti-EGFR antibody.