PLAU and colorectal carcinoma: As levels of expression of caveolin-1, uPAR, and β1-integrin were high in SUM149 cells and we have previously shown that uPA, uPAR, and β1-integrin colocalize in caveolar fractions of colorectal carcinoma cells [12], we isolated caveolae-enriched fractions from SUM149 cells.