Fig. 2. Nuclear tau partially colocalizes with nucleolin. Colocalization of endogenous tau with nucleolar protein nucleolin was analyzed by immunofluorescence and confocal microscopy in human skin fibroblasts and HeLa cells. Each row represents a single optical section of the same nucleus. Upper panels (A,B), show phase-contrast image (A) and fluorescent nucleolin distribution (B) in human fibroblasts. Lower panels (C,D), show phase-contrast image (C) and fluorescent nucleolin distribution (D) in HeLa cells. (E,H) Tau distribution revealed with Tau-1 monoclonal antibody. (F,I) Subnuclear nucleolin distribution detected with nucleolin C23 polyclonal antibody. Merged images of tau with nucleolin are shown on the right for human fibroblasts (G) and HeLa cells (J). Bars, 10 µm (A-D); 5 µm (E-J).