Left: Analysis of ubiquitin expression (brown) in FFPE section of human cerebral cortex of an Alzheimer patient by Immunohistochemistry. Signal was generated with DAB. Counterstain: haemotoxylin (blue). A typical flame-shaped tangle is seen in a pyramidal neuron in the center and is surrounded by dystrophic neurites, also strongly ubiquitin-positive. Both are commonly seen in cortical and hippocampal Alzheimer brain sections and are typical for this disease, but are rare or absent in healthy brain. Right: Western blot analysis of HEK293 cell lysates for ubiquitin expression (green, 1:1,000).  protein standard,  cells maintained in normal medium,  cells treated with 10 uM of proteasome inhibitor lactacystin (Lc) for 16 hours. The smear detected above the 200 kDa standard represents accumulation of ubiquitinated proteins in proteasome inhibitor-Lc treated cells. The prominent band at 8 kDa corresponds to monoubiquitin. The same blot was probed with an antibody to HSP60 as loading control.