Migration of embryonic fibroblasts (E14.5 ± 0.5) assayed with a wound healing assay. (A) Example of cell wounds made by a 200-µl pipette tip at time 0 and after 8 h; d, distance between borders of the cell layer. Closure of the wound was determined at four predetermined positions on each side (arrowheads). (B) Relative narrowing of the distance, d, given in percentage of initial distance at time 0 h. Symbols represent means ± SD from four individual experiments per genotype; straight lines represent linear regression between 1–5 and 6–13 h. (C) Means ± SD of the slopes (% closure/h) of the regression lines from the individual experiments (n = 4), showing that initial migration of KO was faster than that of WT. **, P < 0.01 (two-way ANOVA followed by Sidak’s multiple comparison posttest).