Fig. 6. (A) Fluorescence recovery after photobleaching of the nucleus in starved conditions (upper sequence) and after 30 minutes in FGF4. After the first photobleaching in starved cells, we waited at least 20 minutes to allow complete recovery of fluorescence before proceeding with stimulation and the second photobleaching. Bar, 10 µm. (B) Normalized recovery of the cell indicated by the arrowhead in A. The exponential fit of the fluorescence recovery (continuous lines) is used to compute and the IF. Stimulation caused a faster turnover of ERK2-GFP through the nuclear membrane because the of the recovery decreased from 144 seconds (red trace) to 69 seconds (blue). A similar effect occurred in the upper cell in A (starved =236 seconds; FGF4 =84 seconds). (C,D) Averaged of recovery and IF for starved cells (red symbols) or after stimulation (45 minutes: green, ERK1-KO: green open; 3 hours: dark green; starved overexpressing: magenta; ^**P0.0001; ^*P0.003; °P0.05). Time constants have been measured in cells transfected with both the N- and C-terminal fusions. (E) Scatter diagram showing recovery and CI of all paired cells (red, starved; blue, FGF4; green, serum-treated cells). Broken lines join observations relative to the same cell. Open symbols represent averages and s.e.m. of each group.