What is Cytoskeleton?
[[File:FluorescentCells.jpg|thumb|right|250px|The [[eukaryote]] cytoskeleton. Actin filaments are shown in red, microtubules in green, and the [[cell nucleus|nuclei]] are in blue.]] The '''cytoskeleton''' is a kind of [[scaffold]]ing present in all cells. It is made of [[protein]]. It keeps cell shape, protects the cell and enables cells to move (using structures such as [[flagellum|flagella]] and [[cilium|cilia]]). It helps transport inside the [[cytoplasm]] (the movement of [[vesicle]]s and [[organelle]]s, for example), and in [[cell division]]. The concept and the term (''cytosquelette'', in French) was introduced by French embryologist Paul Wintrebert in 1931.<ref>{{cite journal |author=Frixione E |title=Recurring views on the structure and function of the cytoskeleton: a 300-year epic |journal=Cell Motility and the Cytoskeleton |volume=46 |issue= 2|pages=73–94 |year=2000 |pmid=10891854 |doi=10.1002/1097-0169(200006)46:2<73::AID-CM1>3.0.CO;2-0}}</ref> [[Eukaryote]] cells contain three main kinds of cytoskeletal filaments, which are ''microfilaments'' ([[actin]] filaments), ''intermediate filaments'', and ''microtubules''. They give the cell structure and shape.<ref>{{cite journal |author=Minton AP |title=Confinement as a determinant of macromolecular structure and reactivity |journal=Biophys. J. |volume=63 |issue=4 |pages=1090–100 |date=October 1992 |pmid=1420928 |pmc=1262248 |url=http://www.biophysj.org/cgi/reprint/63/4/1090 |doi=10.1016/S0006-3495(92)81663-6 |access-date=2010-01-14 |archive-date=2008-09-07 |archive-url=https://web.archive.org/web/20080907045024/http://www.biophysj.org/cgi/reprint/63/4/1090 |url-status=dead }}</ref> Cytoskeletal elements interact closely and often with the [[cell membrane]] and the [[endoplasmic reticulum]].<ref>{{cite journal |author=Doherty GJ and McMahon HT |title=Mediation, modulation and consequences of membrane-cytoskeleton interactions |journal=Annual Review of Biophysics |volume=37 |pages=65–95 |year=2008 |pmid=18573073 |url=http://arjournals.annualreviews.org/doi