Figure 1.

(A) Purification of sctPA from MDA-MB-435-conditioned medium. Zymographic analysis of the plasminogen-dependent activity is shown. Lanes 1–5 are 15 μg of protein sample from MDA-MB-435-conditioned medium, 15 μg of protein of elution fraction 5, 0.45 NIH unit of high molecular weight uPA standard, 0.43 NIH unit of commercial sctPA standard, and 6.15 NIH units of elastase. (B) Dose-dependent inhibition of plasminogen activator activity by tPA-blocking monoclonal antibody. A coupled assay for plasminogen activation by free enzyme was performed. The rates of plasminogen activation by 0.4 NIH unit of pure sctPA (solid line) and by 15 ml of fraction 5 (dashed line) are normalized and presented as percentages of the corresponding positive controls in the absence of antibody. The error bars represent standard deviations from two parallel experiments.