Figure 5.
Effect of GIT1 overexpression on transferrin uptake. (a) Immunofluorescence of COS 7 cells that have been incubated with FITC-transferrin for 15 min. (Left) A representative field of cells transiently transfected with either GIT1-Flag (Upper) or dyn K44A-c-myc (Lower), identified by staining with anti-Flag and anti-c-myc antibodies, respectively (Left). (Right) The fluorescence signal of cells from the same field shown on the left that have internalized FITC-transferrin. The arrows point to cells overexpressing GIT1-Flag (Upper) and dynamin II K44A (Lower), whereas the arrowheads point to the nontransfected cells. (b) Quantitative assessment of internalized FITC-transferrin. FITC-transferrin uptake was quantified by assessing the number of transfected cells (GIT1-Flag or dynamin II K44A) that have internalized FITC-transferrin. Results are expressed as percent of FITC-transferrin internalization. Data are means ± SEM of three experiments in which 25–40 cells have been evaluated. *, P < 0.001