Actin contraction is altered by ligand mobility.

<p>(A) Representative time-lapse TIRF images of GFP-actin expressing Jurkat cells stimulated on surfaces with the indicated <i>D</i> and <i>R</i>. The time when cells exhibit the maximum actin spreading was defined as t_max. Scale bars = 10 µm. (B) Corresponding normalized actin fluorescence intensities at t_max (black), t_max+300 sec (red), and t_max+1200 sec along the dashed lines in (A).