CDC42GAP-mediated ERK activity regulates chemokinesis and podosome-like assembly, while CDC42GAP-mediated p38^MAPK activity regulates chemotaxis and restrains filopodia-like formation. Neutrophils were treated with either the MEK inhibitor U0126 or the p38^MAPK inhibitor SB203580 and subjected to migration assays or F-actin and vinculin reorganization. (A) Chemokinesis assessed in the Boyden chamber as in Figure 3A. (B) Chemokinesis in the presence of U0126 assessed in transwells coated with fibrinogen as in Figure 3B. (C) Chemotaxis in the presence of SB203580 assessed in the Boyden chamber. (D) Chemokinesis and chemotaxis in the presence of SB203580 assessed in transwells coated with fibrinogen. All histograms represent the mean ± SD; a representative experiment in triplicate from 3 independent experiments is shown. (E) Neutrophils were prestimulated and seeded on fibrinogen for 30 minutes and examined for F-actin assembly and vinculin structures as in Figure 4B. Note the presence of filopodia in the tail in WT cells treated with SB203580 (arrow). Note the presence of podosome-like structures at the leading edge of the cells in CDC42GAP-deficient cells treated with U0126 (arrow). Representative images from 3 independent experiments are shown. (F) The percentage of WT cells treated with SB203580 displaying more than 1 membrane protrusion and increased filopodia was quantified. (G) The percentage of CDC42GAP-deficient cells treated with U0126 displaying podosome-like structures was quantified. Histograms represent the mean ± SD of 3 independent experiments.