Intermediate filaments are composed of two-chain, a-helical, coiled-coil molecules arranged on an imperfect helical lattice. They have been widely used as markers for distinguishing individual cell types within a tissue and identifying the origins of metastatic tumors. Vimentin is a general marker of cells originating in the mesenchyme and is frequently co-expressed with other members of the intermediate filament family, such as the cytokeratins, in certain neoplasms. Vimentin and Desmin, a related class III intermediate filament, are both expressed during skeletal muscle development. Desmuslin links Desmin to the extracellular matrix and provides structural support in muscle. HOM-TES-103, also known as intermediate filament family orphan 1 (IFFO1), is a 559 amino acid protein that belongs to the intermediate filament family. Ubiquitously expressed, HOM-TES-103 exists as seven alternatively spliced isoforms.