Vimentin is the most common member of intermediate filament (IF) family and one of the main components in cytoskeleton structure. It is expressed during cell development and differentiation in variety of mescencymal cells and cell types derived from the mesoderm. Vimentin is essential in the role of cell integrity and cytoskeletal stability. The reorganization of vimentin, similar to all IF proteins, occurs during different stages of the cell cycle and cell signaling by a site-specific phosphorylation (serine and threonine residues). In particular, p21-activated kinase (PAK) phosphorylates at Ser25, Ser38, Ser50, Ser65 and Ser72 which induces vimentin specific reorganization. During cytokinesis, vimentin is regulated by Rho-kinase (ROCK) and Aurora B through phosphorylation at Ser38 and Ser72. Also, coordinated by ROCK and Aurora B, Plk1 induced phosphorylation at Ser82 plays an important role in vimentin segregation. Vimentin labels mesenchymal cells. In combination with a panel of antibodies, it is used to identify tumor with mesenchymal origin and malignant melanoma. Additionally, vimentin is a useful control marker for proper tissue processing.