Nestin is an intermediate filament protein expressed in dividing cells during the early stages of development in the CNS, PNS and in myogenic and other tissues. Upon differentiation, nestin becomes downregulated and is replaced by tissue-specific intermediate filament proteins. Interestingly, nestin expression is reinduced in the adult during pathological situations, such as the formation of the glial scar after CNS injury and during regeneration of injured muscle tissue. Although it is utilised as a marker of proliferating and migrating cells very little is known about its functions or regulation. In depth studies on the distribution and expression of nestin in mitotically active cells indicate a complex role in regulation of the assembly and disassembly of intermediate filaments which together with other structural proteins, participate in remodeling of the cell. The role of nestin in dynamic cells, particularly structural organisation of the cell, appears strictly regulated by phosphorylation, especially its integration into heterogeneous intermediate filaments together with vimentin or alpha-internexin.