Rac1 activity in LifeAct-GFP–expressing cells leads to cell–cell contact formation. Shown is a time-lapse movie of a photoactivation experiment in control siRNA–transfected MCF10A cells co-transduced with LifeAct-GFP (green) and mCherry-PA-Rac1 (not depicted). PA-Rac1 is activated through the 488-nm laser, also exciting the LifeAct-GFP signal. Frames were taken every 5 s using a confocal microscope (LSM 700; Carl Zeiss) equipped with a 60×, NA 1.4 objective lens.
