Nestin, a large intermediate filament protein (class Type VI) expressed during development and in myotendinous and neuromuscular junctions. Nestin expression is restricted, typically disappearing by E18. Nestin is thought to be a reasonable neuronal marker; however, recent studies have found nestin expression in other cell types such as endothelial cells {Folia Biologica, 44(5):155, 1998}. Nestin identifies the most primitive neuroepithelium but also identifies many other embryonic tissues, so it is not specific for CNS. Nestin expression is seen in almost all GBMs (Glioblastoma mulitformes) and many melanomas (both primary and metastatic) but not in any metastatic carcinoma.