Profile of cathepsin B, uPA, uPAR, β1-integrin and caveolin-1 expression in SUM149 and SUM190 cells. Expression of intracellular proteins was analyzed in duplicate samples of cell lysates, whereas expression of secreted proteins was analyzed in duplicate samples of conditioned media. Lysates and conditioned media of 2D cultures of SUM149 and SUM190 cells were equally loaded based on the protein concentration of the respective cell lysate and resolved by 10% SDS-PAGE. Proteins were transferred to a nitrocellulose membrane and immunoblotted with (a) an anti-cathepsin B (cat B) polyclonal antibody (bands represent proform (43 kDa), intermediate (38 kDa), single chain mature (31 kDa), and heavy chain (25/26 kDa) of double chain mature cathepsin B); (b) an anti-uPA antibody; (c) anti-uPAR, anti-β1-integrin, anti-caveolin-1 (cav-1) antibodies and (d) anti-β-tubulin monoclonal antibody with the concentration of α-tubulin in the cell lysate serving as a loading control for both cell lysates and their respective conditioned media. uPA, urokinase-type plasminogen activator; uPAR, urokinase receptor.