NIH3T3 cells transfected with the GFP-TN-C promoter construct were plated onto the different surfaces at the same density, and at 24 hours after plating they were fixed, stained with DAPI and Texas Red-C2-maleimide. Cells in 50 fields were imaged and analyzed on each sample using automated digital microscopy and image analysis software. Relative GFP fluorescence intensity is plotted versus relative cell number and plots show data from at least two independent experiments each consisting of duplicate samples. Thin films of fibronectin (◇); thin films of fibrillar collagen (▲); and thin films prepared from the lower concentration collagen (●). Error bars reflect the standard deviation of a minimum of four samples derived from at least two replicate experiments. Control cells (□) were not transfected with the GFP construct, and so their intensity reflects autofluorescence. Inset: A 3-dimensional rendering of the cellular GFP fluorescence intensity data ≥ 200,000 fluorescence units.