This MAb reacts with a 58kDa protein identified as vimentin. It reacts with a non-hematopoietic epitope of vimentin and shows no cross-reaction with other closely related intermediate filament proteins (IFP's) such as desmin, keratin, neurofilament, and glial fibrillary acid protein.Vimentin is ubiquitously expressed in mesenchymal cells such as fibroblasts, smooth muscle cells, and endothelium. Antibody against vimentin is useful as part of an antibody panel for differential diagnosis of tumors of unknown origin.Ab-2 does not react with leukocyte common antigen-positive tissues such as lymphomas and leukemias.