Fig. 5. Membrane cholesterol and caveolins do not regulate SFK signalling linked to PDGF-induced dorsal ruffle formation. (A) SFKs are required for PDGF-induced dorsal ruffle formation. Top panel: typical effect obtained with SFK inhibition on PDGF-induced dorsal ruffle formation. Bottom panel: statistical analysis of PDGF response (% of cells with dorsal ruffle) in cells expressing indicated construct or treated with the SFK (SU6656 5 µM) or the MEK (U0126 10 µM) inhibitor as shown. (B) Dorsal ruffle formation is not affected by cholesterol depletion. Top panel: typical effect obtained with membrane cholesterol depletion on PDGF-induced dorsal ruffle formation. Bottom panel: statistical analysis of PDGF response (% of cells with dorsal ruffle) of cells expressing indicated caveolin constructs, treated with indicated cholesterol-depleting agents, or grown in LPDS as shown. NIH 3T3 grown on coverslips were transfected or not with indicated construct, serum-starved, treated with SU6656 (5 µM) for 30 minutes and stimulated with PDGF (15 ng/ml) for 10 minutes. Cells were fixed and processed for actin staining using Rhodamine-phalloidin and ectopic protein expression. Cav-3DGV was co-transfected with trace amounts of GFP construct to visualise transfected cells. Cells expressing SrcK^– (A) or Cav-3DGV (B) constructs are indicated by arrows. The mean percentage of cells that formed dorsal ruffles and the s.d. from three to five independent experiments are shown.