Figure 2

Endothelial cell migration on Vn and uPA/PAI-1 co-localization are affected by a uPAR^-/- deficiency: (A) Absence of uPAR expression decreased EC migration on Vn but not on collagen. Quiescent WT and uPAR^-/- ECs were plated to confluency on Vn- and collagen-coated 6-well dishes and a scratch induced. Migration was induced by the presence of VEGF (10 ng/ml) and images of the scratch area were acquired immediately after the scratch and after 24 hr of incubation at 37°; C/6.5% CO₂. The number of cells that had migrated in the scratch area was counted and graphed as percent of migrated WT cells. The graph represents the mean ± SEM of three independent assays each performed in triplicate. Significance levels (*) indicates p value of < 0.05 between WT and uPAR^-/- ECs. (B) uPA/PAI-1 co-localization is cytoplasmic in migratory uPAR^-/- ECs. Fixed cells were stained with antibodies against uPA (green, Alexa Fluor 488) and PAI-1 (red, Alexa Fluor 647). Co-localization of uPA/PAI-1 in WT cells was observed along the focal adhesions or cell membrane (arrows). (C) In the uPAR^-/- ECs uPA/PAI-1 co-localization was observed as extensive blobs within the cytoplasm (arrows).