The role of VASP phosphorylation in random movement and cAMP-driven chemotaxis. A, Paths of cell movement from 15 min tracking of chemotaxing cells are shown. Chemotaxis or random movement of aggregation-competent cells were captured using time-lapse microscopy at 3 sec intervals and analyzed with MetaMorph software. Asterisks indicate the direction of the tip of 100 μM cAMP-filled micropipette. B, Speed of random motility measured from 2-5 experiments is plotted as a bar graph. (**p<0.01, *p<0.025 compared to null cells.) C, Chemotactic movement of cells from 2-4 experiments was analyzed and the speed is shown. Note that unphosphorylated VASP exhibits higher cell speed than VASP and SD cells during chemotaxis. (**p<0.0001, *p<0.01 compared to null cells; #,@ p<0.02). D, Effect of VASP phosphorylation on directional efficiency of chemotactic cells. Directional efficiency is defined as the ratio of Euclidean distance (length of direct path) to the actual cell path and plotted as a bar graph. (*p<0.0001 compared to null cells. # p<0.01 by unpaired t-test).