FIG. 7.

16E5 does not slow the initial endocytosis of prebound EGF. Trafficking of Alexa Fluor 488-EGF bound to the surface of EGF-starved LXSN-HFKs, 16E5-HFKs (with or without the AU1 epitope tag), and 16E5(−20)-HFKs (which express a 20-amino-acid C-terminal 16E5 deletion mutant) at 4°C (0 min) and after warming to 37°C for 5 min or 30 min. Cells were fixed at the indicated times to allow high-resolution imaging using a 63× oil immersion objective lens. Scale bar, 20 μm. Images taken at 30 min were analyzed using Kodak MI software to determine the size of EGF-containing endosomes. Bar graphs indicate the percentages of endosomes that fall within a defined range of sizes: 0 to 165 pixels (group 1), 166 to 331 pixels (group 2), or >331 pixels (group 3).