Expression of intact uPAR inversely correlates with cell density. HUVECs were seeded in different densities (indicated as cells per centimeter squared) and grown in complete growth medium for 4 days. Photographs were taken before harvest. (A) Immunocytofluorimetric detections of cell surface uPAR (nonpermeabilized cells; gray line) and total uPAR (permeabilized cells; black line). The total amount of uPAR decreases with cell density. Geometric means for fluorescence intensities were calculated. Filled gray bar represents IgG. Data are mean ± SEM. (B) Relative quantitative reverse transcriptase-polymerase chain reaction of uPAR mRNA normalized to porphobilinogen deaminase. Data are mean ± SEM. *P < .05. (C) Representative Western blot for uPAR of lysates of HUVECs. Mainly intact (ie, full-length) uPAR (∼ 44 kDa) was detected in contrast to cleaved uPAR (30 kDa).