Fig. 5. PAK1, Cdc42 and myosin Va localization in human melanocytes. (a) Immunofluorescence microscopy for Cdc42 (1) and PAK1 (2) was performed on cultured human melanocytes. Cdc42 displayed a vesicular pattern with localization along the length of the melanocyte dendrite as well as in the Golgi area. PAK1, in contrast, was distributed diffusely in the cytosol, in the Golgi area as well as in the dendrites. Bar, 30 µm. (b) The results of double labeling of melanocytes with antibodies to TRP-1 (mel-5) and PAK1 are shown. Images (1,4) show mel-5 localization; images (2,5) show PAK1 localization, images (3,6) are cells viewed with filters to detect both fluorescein-isothiocyanate and Texas Red. PAK1 and TRP-1 colocalize predominantly in the peri-nuclear area (3); however colocalization is also observed along the melanocyte dendrite (6; arrowhead). Bar, 30 µm (1-3); bar, 10 µm (4-6). (c) Melanocytes stained with antibodies to myosin Va show the expected localization of myosin Va at the tips of melanocyte dendrites, consistent with the presence of melanosomes at this site. Myosin Va staining was also detected along the length and at the tips of melanocyte filopodia. Bar, 2 µm.

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