Immunofluorescent analysis of Ubiquitin in HeLa cells. Cells were stained with a ubiquitin polyclonal antibody (Product # PA1-10023) at a dilution of 1:1,000 as seen in red, stained with a Vimentin polyclonal antibody (Product # PA1-10003) at a dilution of 1:10,000 as seen in green, and with DAPI staining the nuclear DNA as seen in blue. A) Control HeLa cells maintained in normal medium, B) HeLa cells treated with 10µM of the proteasome inhibitor lactacystin (Lc) for 24 hours. Proteasomal inhibition leads to formation of strongly ubiquitin positive cytoplasmic inclusions. Note the diffuse cytoplasmic ubiquitin staining in control cells and the well-defined ubiquitin positive inclusions in the Lc treated cells.