Fig. 6. Huntingtin is found at the centrosome in a fraction of the cell population. (A) 3T3 cells were stained with both the anti-huntingtin antibody directed against the first 17 residues of the protein (green) and a monoclonal anti--tubulin (red) antibody, and examined with an epifluorescence microscope. In a large fraction of the cells the centrosome is clearly labeled by both antibodies (arrows). The centrosome of the lower cell of the upper panel is not stained by the anti-huntingtin antibody. (B) Cells were examined by confocal microscopy and double-labeled pixels were displayed in white. The centrosome shows clear colocalization of huntingtin and -tubulin.