Endobrevin is localized mainly to the later compartment of the early endosomes. A431 cells were incubated with monoclonal antibodies against transferrin receptor on ice, shifted to 37°C, and incubated for different periods of time at 37°C before processing for indirect immunofluorescence microscopy. Cells were double labeled for endobrevin (A, C, E, and G) and transferrin receptor (B, D, F, and H). Bar, 10 μm.