Video 2 - Movement of POS phagosomes along microtubules in an RPE cell. Cultured primary mouse RPE cells were transfected to express GFP-alpha-tubulin and incubated with mouse POSs (red) labeled with Texas red-X succinimidyl esters. The cells were analyzed by time-lapse microscopy, using a spinning disk confocal microscope system (UltraVIEW ERS). Single z-plane images were collected for each color sequentially, with one dual-colored frame obtained every second for 2 min. The playback rate of the movie is 10 frames per second (i.e., 10 times real speed). Bar, 1 µm. Images of individual frames of this video are shown in Fig. 1 B.