Disrupting actin filaments alters CLIP-170 localization in B cells. A20 cells that had been transfected with CLIP-170-GFP were pre-treated with 2 μM latrunculin A for 5 min. The cells were allowed to spread on anti-IgG-coated coverslips for 10 min and then imaged by TIRFM with a 100 nm TIRF depth. Images were acquired every 30 ms. The video is played back at 75 frames per second (2.25X real time). The CLIP-170-GFP fluorescence signal is shown as a heat map in which low fluorescence intensity is purple and high fluorescence intensity is white. Note that this video is from the same experiment as the video shown in Supplementary Movie 8, which depicts a cell from the control sample that was not treated with latrunculin A.