Fig. 3. Knockdown of FAK expression induces cell elongation. (A,B) Phase-contrast images, western blot analysis of FAK protein expression and quantification of cell elongation in control cells, FAK-siRNA treated Rat2 cells (A) or FAK-shRNA treated NIH3T3 cells (B). The extent of FAK knockdown was determined by western blotting and compared with expression of paxillin. (C) Western blot analysis of FAK expression in wild-type Rat2 cells, Rat2 cells expressing LacZeo and Rat2 cells expressing GFP-tagged chicken FAK. Endogenous FAK expression was substantially reduced in wild-type (wt), control-transfected cells (Lzeo) and in cells expressing GFP-tagged chicken FAK (GFP-FAK) following treatment with FAK siRNA (right three lanes) as compared with control siRNA-treated cells (left three lanes).The level of expression of GFP-tagged chicken FAK remained unchanged upon treatment with either control or FAK siRNA. Actin levels indicate the equal loading of sample in each lane. (D) Expression of GFP-FAK decreases cell elongation following FAK knockdown using siRNA. The images on the left illustrate the reduced immunostaining of FAK observed in cells treated with FAK siRNA. The images on the right illustrate the continued expression of GFP-tagged chicken FAK (GFP-FAK) in cells treated with control and FAK siRNA. Graphs panels A, B and D show cell-shape measurements that were assessed by determining the elongation factor for cells treated with either siRNAs or shRNAs.