Fig. 5. Deficient actin dynamics in 3 integrin mutant cortical cells. E14 cortical cells were electroporated with EGFP-actin and time-lapse images of the actin cytoskeleton at the leading edges was recorded after 48 hours. The actin cytoskeleton of the tips of the wild-type cells shows very active remodeling (A; see actin microspikes in regions marked with arrowheads, ^v indicates dynamic changes in their assembly and disassembly). (C) Higher magnification view of the outlined area in A. Arrows indicate actin microspikes undergoing remodeling. By contrast, actin cytoskeleton of leading edges of the 3-deficient cells display significantly reduced dynamic activity (B; compare actin microspikes in regions marked with arrowheads, compare ^v with similarly marked actin microspikes in A). (D) Higher magnification view of the outlined area in B. Arrows indicate actin microspikes that are considerably less dynamic than those from wild-type cells. (E) Re-expression of 3 integrin rescued actin dynamics deficits in 3 integrin mutant cells. Arrow indicates an actin microspike undergoing dynamic remodeling at the leading edge of an 3 mutant cell transfected with 3 integrin DNA. Time elapsed since the beginning of observations is indicated in minutes. Scale bar: 10 µm in A,B; 3 µm in C-E. (Also see Movies 5-7 in the supplementary material.)