Nestin is a type IV intermediate filament protein expressed by neuroepithelial stem cells and which has been proposed to represent a marker for putative islet stem cells. It is a high molecular weight protein with a terminus greater than 500 residues. Nestins are expressed by several types of cells during development, mostly in dividing cells of the Central Nervous System, Peripheral Nervous System and myogenic tissues. It also represents the progenitor population of neural stem cell origin. The role of nestin in dynamic cells, particularly structural organization of the cell, appears strictly regulated by phosphorylation, especially its integration into heterogeneous intermediate filaments together with vimentin or internexin. Nestin has recently received attention as a marker for detecting newly formed endothelial cells.