Progress of fibrinolysis in fibrin₅ formed using 5nM thrombin with delF-tPA-GFP. The 4 panels are snapshots of the distribution of delF-tPA-GFP during fibrinolysis at the times indicated in the upper corner. Initial binding and concentration of the delF-tPA-GFP to the surface of the clot were slow, but after 10 minutes a narrow zone of concentrated activator formed. Subsequently, some tPA diffused ahead of the fibrin-buffer interface and was associated with some fibrin aggregates; a proportion of delF-tPA-GFP also remained close to the fibrin-buffer interface appearing as a “starburst” pattern.