Fig. 2. GFP-Rab7 associates with phagosomes within 60 seconds of internalization. GFP-Rab7 expressing cells were allowed to attach to glass coverslips and mounted in a chamber to facilitate imaging by confocal microscopy. RITC-labeled yeast were added to the growth media and images were captured every 5 seconds. Selected images of a single experimental series are shown. Note that the newly internalized yeast particle in the right portion of the cell does not receive GFP-Rab7 until at least 20 seconds after uptake (panel labeled 60''). The particle in the left portion of the cell appears to be surrounded by GFP-Rab7 vesicles during internalization but a closer inspection of the cup, particularly at 0 seconds and 40 seconds reveals Rab7-free areas. Bar, 5 µm.