Figure 1: (a) Visualization of the stable transfected monoclonal cell line expressing GFP-actin. GFP-actin is present in the cytoplasmic pool surrounding the nucleus and in F-actin structures such as stress fibers (arrow) and the cortical skeleton. (b) Effect of PDGF-BB stimulation on GFP-actin expressing C3H10T1/2 mouse fibroblasts. Recording of images started two minutes after the addition of PDGF-BB. Dorsal circular ruffles start at the edge of cells (cell A, arrows). During the response, circular ruffles move across the surface and contract. The time from the formation of these ruffles until the full disappearance is 17 minutes. Bar represents 50 μm. (c) Effect of PDGF-BB stimulation on C3H10T1/2 mouse fibroblasts visualized with environmental scanning electron microscopy (ESEM). Serum-starved mouse C3H10T1/2 fibroblasts exhibit an extremely flat cell morphology with a nucleus bulging out (A). Five minutes after stimulation with PDGF-BB, a large circular ruffle is formed (B) stretching out over a large part of the cell surface. After 15 minutes, circular ruffles are further contracted, extend further in the dorsal direction, and exhibit a thicker rim. Imaging conditions: HV = 6 kV at 100%RH. Bar represents 20 μm.