uPAR is found in endocytic compartments in the absence of ligands in HEK293-uPAR cells.

<p>Immunofluorescence of HEK293-uPAR cells labeled with a polyclonal anti-uPAR antibody and imaged by confocal microscopy. Image 2 (left), shows the predominant location of uPAR in lamellipodia-like protrusions and in intracellular compartments, including large vesicles (arrowheads). Image 2 (right), shows a different z-axis of the same cell where large putative macropinosomes are evident (arrowheads, inset 3× magnification). Scale bar 10 µm. Image 2B shows HEK293-uPAR co-stained with the early endocytic marker EEA-1 and the late endocytic/lysosomal marker LAMP-1. In these cells, internal uPAR (green) is not present in the lysosomal compartment as shown by the lack of overlap with LAMP-1 (red). On the other hand, intracellular uPAR (green) completely overlapped with EEA-1 positive puncta (arrowheads). Note the large lamellipodia-like protrusions induced by uPAR expression. Scale bar 10 µm. Insets are magnifications of the relevant areas.