Fig. 1. WIP overexpression increases PDGF-induced dorsal ruffle formation. (A) Fluorescence micrographs of TRITC-phalloidin stained NIH 3T3 fibroblasts transfected with control plasmid (3T3pcDNA) or with WIP coding sequence (3T3pcDNA-WIP) before and after PDGF challenge. Cells were grown on glass coverslips, serum starved for 4 days in the presence of 0.5% FBS, stimulated or not with PDGF-bb (50 ng ml^-1) for 8 minutes and then fixed and labeled with TRITC-phalloidin to visualize actin filaments. Indicated cells (Wort+PDGF) were pretreated with 12 nM wortmannin for 30 minutes at 37°C and then stimulated with PDGF and stained as described. Magnification 400x. (B) Electron micrographs of cortical actin network of NIH 3T3pcDNA-WIP (left) and NIH 3T3pcDNA (right) fibroblasts stimulated as described above. (C) Frames of phase-contrast microscopy capture of NIH 3T3pcDNA and NIH 3T3pcDNA-WIP fibroblasts grown on glass coverslips and stimulated at 37°C with PDGF for the indicated times. Frames were processed using Microsoft PowerPoint software. Arrows point to membrane ruffles. Magnification 400x.