Fig. 4. Influence of VASP phosphorylation on cell area after the addition of NO donor. (a) Sequence of frames taken from Movie 1 (see supplementary material), showing distribution of WT GFP-VASP (green) in transfected human PTEC before (t=0 minutes) and after (t=30 minutes) addition of NO donor. The outline of the cells is shown in the phase-contrast micrographs. Merged images are on the right. Bars, 10 µm. Arrowheads mark edge of cell. (b) Mean cell area normalized to that just prior to addition of NO donor. Black bars, cells transfected with WT GFP-VASP; white bars cells transfected with S239A GFP-VASP. Areas were measured 30 minutes before (Control) and after (After NO donor) NO donor addition. Values are the mean ± s.e.m.; n=12 or more. Reduction in area in cells transfected with WT GFP-VASP following NO donor addition was significantly reduced compared with control value (P<0.01, two-tailed t-test).