Visualization of de novo assembly and release of MLV in living cells. A HEK293 cell generating MLV labeled with Gag-YFP (red) was monitored using spinning disc confocal microscopy over a period of 1 h and 12 min. A z-stack of 13 images covering 4 Âµm was acquired every 59 s. To generate the QuickTime video, the 13 frames were merged into a single image using Improvision Volocity and Openlab software. The last frame of the QuickTime video displays the merged image of all frames of the time-lapse video. The video is played at 10 frames/s. The four labeled particles correspond to the particles AâD presented in Figure 2A.