Figure 2.

The HSF1 protein is highly mobile within the granules. FRAP experiment on living HeLa cells transiently transfected with a HSF1–GFP construct and exposed at 42°C for 15 minutes. A portion of a stress granule was photobleached by a 1-minute exposure to the 488 nm laser line of the confocal microscope. Averaged images were acquired at different time points: before photobleaching (a), just after photobleaching (b), 20 seconds after photobleaching (c), 45 seconds after photobleaching (d), 1 minute 15 seconds after photobleaching (e), and 2 minutes 45 seconds after photobleaching (f). (Bar = 5 μm.)