<p><b>(A)</b> Intracellular uPA or (<b>B</b>) PAI-1 protein levels in cellular extracts of transfected and non-transfected MDA-MB-231 cells were analyzed by Western blot using an antibody to either uPA (A) or PAI-1 (<b>B</b>). (<b>A</b>) Top panel (short exposure) and the lower panel (longer exposure). Total protein concentration was determined and 21 μg protein was added at each experimental condition. The upper band corresponds to the PAI-1/uPA complex (<b>A-B</b>). (<b>C</b>) Intracellular uPA activity was determined in cellular extracts using a chromogenic assay in non-transfected cells (0) and cells transfected with 100 pmol RNA aptamers. Each experiment was performed at least three times with comparable results. **p<0.01, *p<0.05.</p
