Fig. 2. Response of cell migration and traction forces to the application of Gd³⁺. Phase contrast images (A-C) of a migrating NIH3T3 fibroblast, recorded before and at specified time points after the application of 100 µM Gd³⁺. At steady state, the cell showed no apparent effect on the spread morphology or local protrusive activities (arrows, C). However, forward migration of the cell was inhibited. Asterisks mark a fiduciary reference point on the substratum. The corresponding traction stress images (D-F), with different colors representing the magnitude, from 1.04x10² dynes/cm² (violet) to >1.00x10⁵ dynes/cm² (red), showed a striking decrease in traction stress following Gd³⁺ application. Scale bar: 20 µm.