Fig. 6. PDGF response and paxillin and vinculin distribution in C3G mutant MEFs. FITC-phalloidin staining for filamentous actin of homozygous C3G mutant MEFs (A,B) or wild-type MEFs (C), plated onto gelatine-coated coverslips in 24-well plates in DME plus 10% FBS, serum-starved for 16 hours and treated for 10 minutes with 10 ng/ml PDGF-BB. Note the formation of rings of filamentous actin. Actin rings were significantly more numerous (B) and larger (A) in C3G mutant MEFs as compared to wild-type MEFs (C). (D) Graphic representation of the PDGF-BB response of C3G mutant (gt/gt) vs. wild-type MEFs. For a<b, a<c and b<c P<0.001. Paxillin (E,F) and vinculin (G,H) immunostaining of C3G mutant and wild-type MEFs. Mutant MEFs plated onto gelatine-coated cover slips in DMEM plus 10% FBS and serum-starved for 16 hours formed considerably fewer paxillin-positive focal adhesions, which were also reduced in size (E compared with F). This phenomenon can also be seen in cultures without serum in figure 8. Likewise, vinculin-positive cell adhesions are reduced in number and size (G compared with H). Bar represents 27 µm in A,B,C,E,F and 11 µm in G,H.