Fig. 8. Arp2/3 complex binding is required for cortactin to interact with dynamin 2. (A) Expression of cortactin fusion proteins was analyzed by immunoblotting whole cell lysates with cortactin antibody. (B) 2x10⁵ Cells expressing cortactin-GFP fusions were seeded on a 12-well plate, grown in a serum-free medium at 37°C for 30 minutes and incubated with biotin-transferrin for 40 minutes on ice to allow sufficient binding. Endocytosis was initiated by incubation at 37°C for the times as indicated and terminated by placing on ice. The treated cells were then subjected to ELISA-based biotin-transferrin uptake assay as described in Materials and Methods.