Vimentin is a member of the intermediate filament family of proteins that is especially found in connective tissue. Intermediate filaments are an important structural feature of eukaryotic cells. They, along with microtubules and actin microfilaments, make up the cytoskeleton. Although most intermediate filaments are stable structures, in fibroblasts, vimentin exists as a dynamic structure. This filament is used as a marker for mesodermally derived tissues, and as such can be used as an immunohistochemical marker for sarcomas.