Vinculin activation and F-actin binding are required for promoting nascent FA and reducing mature FA. (A) SDC fluorescence micrographs of Vcl-KO MEF expressing the indicated EGFP-vinculin cDNA, immunofluorescence-stained for cortactin and paxillin. Bars, 2 µm. (B) Paxillin intensity distribution along line scans perpendicular to the leading edge of Vcl-KO MEF expressing the indicated EGFP-vinculin cDNA (mean of 20 cells/condition). (C) Box and whisker-plot of mean FA size in Vcl-KO MEF expressing the indicated EGFP-vinculin cDNA and immunofluorescence stained for paxillin as FA marker; n = 11 (nontransfected), n = 9 (WT), n = 9 (PA), n = 12 (ΔAB), n = 10 (PA-ΔAB), and n = 17 (Vh) cells/condition; means indicated; *, P < 0.05, Student’s t test. (D) Box and whisker plot of FA size distribution in Vcl-KO MEF expressing the indicated EGFP-vinculin cDNA and immunofluorescence stained for paxillin as FA marker; n = 11 (nontransfected), n = 9 (WT), n = 9 (PA), n = 12 (ΔAB), n = 10 (PA-ΔAB), and n = 17 (Vh) cells/condition; means indicated; *, P < 0.05, Student’s t test.