Fig. 2. Visualization of PAI-1-GFP in cellular migration tracks. Schematic of a pEGFP-1-based vector in which a chimeric transcript consisting of 1.3 kb of PAI-1 coding sequences and GFP is expressed under the control of a 0.8 kb PAI-1 `promoter' (A). Transfection of RK cells and reseeding in serum-containing medium resulted in synthesis of PAI-1-GFP detected initially in perinuclear Golgi-like structures (B). Approximately 6-12 hours later, PAI-1-GFP can be found in the matrix (probably vitronectin)-rich undersurface region upon removal of cells with saponin (C). The green `footprint' of a single cell is shown in C. Seeding of PAI-1 promoter-PAI-1 coding-GFP transfectants at low density in EGF-containing medium provides for the clear visualization of the chimeric PAI-1-GFP protein in cellular migration trails (D). The small bright image at the extreme right of the trail is the cell body. Transfection of RK cells with the PAI-1 promoter-PAI-1 coding-GFP vector followed by growth to confluency and subsequent scrape injury indicated that the resulting motile population deposited GFP-'tagged' PAI-1 into the cellular migration trails similar to that illustrated in D.