Fig. 1.

HeLa cells internalize LFn-GFP in the absence of PA, but do not internalize GFP. HeLa cells were incubated with Texas red-conjugated transferrin and GFP (a and c) or LFn-GFP (b and d) for 1 hr (a and b) or 2 hr (c and d) and imaged by confocal microscopy. (Right) Overlay of red and green staining. (Center) Uptake of transferrin in red. (Left) Internalized LFn-GFP or GFP in green. Similar results were found for COS cells (data not shown).