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Fig. 5. Transferrin localization and dynamics in the presence of Grb2-YFP or
NSH3m-YFP. (A) Transferrin uptake by COS-7 cells co-expressing EGFR-CFP with
either wild-type Grb2-YFP (top) or NSH3m-YFP (bottom) was monitored by
confocal time-lapse imaging. Images were collected 20 min after EGF
stimulation following 40-min incubation with transferrin-TRITC. (B) Uptake and
sequestration of biotinylated Tfn (B-Tfn) in COS-7 cells was measured by
avidin inaccessibility (See Materials and Methods). Assays were performed in
the absence (open symbols) or presence of EGF (closed symbols). Data shown are
representative of three independent experiments.