Left: Immunofluorescence staining of E18 hippocampal neurons with chicken anti-Tau antibody C-1691-100 (red). Ubiquitin C-terminal Hydrolase 1 (UCHL1), an abundant cytoplasmic protein of neurons which is concentrated in the perikarya, was double-labelled with M-1407-100. Since the perikarya contain both UCHL1 and Tau, the red and green signals superimpose resulting in yellow color. Neuronal processes, which contain relatively much more tau, appear red. Cell nuclei were stained with DAPI (blue). Right: Western blot analysis of tau protein expression in tissue (antibody dilution: 1:10,000).  protein standard,  rat brain,  rat spinal cord,  mouse brain,  mouse spinal cord. Tau protein is expressed as multiple isoforms of different molecular weight, and so appears as multiple closely spaced bands in the region of the blot in the range from 48 kDa to 67 kDa.