T Plastin is a representative of an important family of actin-cross-linking and -bundling proteins that organize most of the actin networks in cells. T Plastin is associated with the actin core bundle of microvilli, stereocilia and microspikes in epithelial cells and was proposed to participate in the assembly of these structures. In mesenchymal cells, T plastin localizes to focal adhesions and the leading edge, a broad lamellar membrane extension harboring a dynamic branched actin network. Recent studies have shown that T plastin has the potential to be a Sezary cell-specific marker valuable for diagnostic and treatment of Sezary syndrome.