Fig. 4. GFP-IMP1 colocalises with microtubules and F-actin. NIH 3T3 cells that stably express GFP-IMP1 were fixed and stained with anti-tubulin antibody or anti-vimentin and phalloidin and examined by confocal microscopy. (A) The simultaneous detection of GFP-IMP1 (green) and microtubules (red) and their colocalization (arrow). (B, upper panel) The simultaneous detection of GFP-IMP1 (green), microfilaments (red) and microtubules (blue). The arrow in the overlay frame indicates the colocalization of F-actin and GFP-IMP in the lamellipodia. (B, lower panel) The detection of GFP-IMP1 (green), vimentin (blue) and microfilaments (red). (C, upper panel) Cells treated with nocodazole. Most GFP-IMP1 collapses into large aggregates, but a fraction of GFP-IMP1 remains anchored in the lamellipodia for more than 1 hour. (C, lower panel) Time-lapse microscopy of GFP-IMP1 after cytochalasin D treatment. At these short time points, the integrity of the cell is intact, but anchoring in lamellipodia has disappeared.