Fig. 7.

Loss of vimentin or plectin inhibits recruitment of Rac1 to α6β4 integrin puncta. (A) A549 cells infected with an adenovirus encoding GFP–Rac and expressing the indicated siRNA were immunostained for α6 integrin and imaged by TIRF microscopy. A magnified image of the boxed areas are shown in the right-hand panels. The yellow color in the inset in the top set of panels indicates colocalization, whereas there is little, if any, yellow in the images of cells in which vimentin or plectin were knocked down. Scale bars: 10 µm (main images) and 5 µm (magnified images). (B) Quantification of the relative intensity of GFP–Rac at puncta. 3 experiments, n=106 (Ctrl-siRNA), n=59 (VIM-siRNA1), n=32 (VIM-siRNA2), n=55 (PLEC-siRNA). ***P<0.001 (pairwise one-tailed Wilcoxon rank sum tests with Bonferroni correction). Graph shows mean±s.e.m. (C) A model depicting the role of α6β4 integrin in localizing vimentin filaments to the cell edge and the effect on cell signaling and directed migration.