FIGURE 3:

Tfn, but not EGF, passes through the PS-positive compartments throughout its trafficking process. HeLa cells were serum starved for 3 h and then incubated at 4°C for 50 min with Alexa Fluor 555–conjugated Tfn or EGF. Cells were washed and chased at 37°C for the indicated times, fixed, and mildly permeabilized with digitonin. The cells were then incubated with rEGFP-LactC2, washed, and fixed again before mounting. Scale bars: 20 μm.