Time-lapse assessment of lipid agonist-induced HT1080 cell motility on 2D collagen substrates versus 3D collagen matrices. Nuc-GFP HT1080 cells were seeded on 2D plastic dishes coated with 50 μg/ml of collagen or embedded within a 3.75 mg/ml type I collagen matrix and their motility was analyzed using Metamorph® software. Digital fluorescent images were acquired every 15 minutes and arranged in sequential order. A single cell is shown either moving on top of a dish (2D) or through 3.75 mg/ml collagen matrix (embedded in 3D) at 6 hour intervals for 24 hours. Tracings (generated by Metamorph®) of the continuous movement of these cells over the 24 hour time period are shown by the blue lines. (Note: Metamorph® creates a yellow line on a black background which is difficult to see. Therefore, the images were inverted to turn the yellow line blue and the black background white.) A blue (yellow) circle indicates the current position of the cell and a black (white) circle indicates the previous position. Subsequent tracings were converted to grayscale. Magnification = 20×. Scale bars = 50 μm.