Fig. 2. Map of fusion sites of post-Golgi vesicles. NRK fibroblasts were microinjected with cDNA encoding LDLR-GFP and imaged using TIR-FM with a temporal resolution of 5 frames per second between 10 minutes and 60 minutes after the release of the Golgi block. Cells were outlined (yellow line) by thresholding the epifluorescence image against the background. Epifluorescence images indicate the LDLR-GFP load in the Golgi before the release of the Golgi block (grey level). The sites of fusion are indicated by either yellow crosses or cyan stars, depending on whether the fusions were complete or partial, respectively. For the migrating cells (C,D), the direction of the leading edge is indicated by white arrows. Stationary (A,B) and migrating (C,D) cells are either untreated (A,C) or treated with 10 µM nocodazole (B,D) during the last hour of the 3-hour Golgi block. Scale bars, 10 µm.