Editing Mitosis (section)

===Cell rounding===
[[File:Cell-shape-mitosis.png|thumb|right|250px|Cell shape changes through mitosis for a typical [[animal cell]] cultured on a flat surface. The cell undergoes [[mitotic cell rounding]] during spindle assembly and then divides via [[cytokinesis]]. The [[Cell cortex|actomyosin cortex]] is depicted in red, DNA/chromosomes purple, [[microtubules]] green, and membrane and retraction fibers in black. Rounding also occurs in live tissue, as described in the text.]]
{{main|Mitotic cell rounding}}
In animal tissue, most cells round up to a near-spherical shape during mitosis.<ref name="Sauer-1935" /><ref name="Meyer-2011" /><ref name="Luxenburg-2011" /> In [[epithelia]] and [[epidermis]], an efficient rounding process is correlated with proper [[mitotic spindle]] alignment and subsequent correct positioning of daughter cells.<ref name="Meyer-2011" /><ref name="Luxenburg-2011" /><ref name="Nakajima-2013" /><ref name="Cadart-2014" /> Moreover, researchers have found that if rounding is heavily suppressed it may result in spindle defects, primarily pole splitting and failure to efficiently capture [[chromosomes]].<ref name="Lancaster-2013" /> Therefore, [[mitotic cell rounding]] is thought to play a protective role in ensuring accurate mitosis.<ref name="Cadart-2014" /><ref name="Lancaster-2014" />

Rounding forces are driven by reorganization of [[F-actin]] and [[myosin]] (actomyosin) into a contractile homogeneous [[cell cortex]] that 1) rigidifies the cell periphery<ref name="Lancaster-2014" /><ref name="Maddox-2003" /><ref name="Matthews-2012" /> and 2) facilitates generation of intracellular [[hydrostatic pressure]] (up to 10 fold higher than [[interphase]]).<ref name="Stewart-2011" /><ref name="Fischer-Friedrich-2014" /><ref name="Ramanathan-2015" /> The generation of intracellular pressure is particularly critical under confinement, such as would be important in a tissue scenario, where outward forces must be produced to round up against surrounding cells and/or the [[extracellular matrix]]. Generation of pressure is dependent on [[formin]]-mediated [[F-actin]] nucleation<ref name="Ramanathan-2015" /> and [[Rho kinase]] (ROCK)-mediated [[myosin II]] contraction,<ref name="Maddox-2003" /><ref name="Stewart-2011" /><ref name="Ramanathan-2015" /> both of which are governed upstream by signaling pathways [[RhoA]] and [[ECT2]]<ref name="Maddox-2003" /><ref name="Matthews-2012" /> through the activity of [[Cdk1]].<ref name="Ramanathan-2015" /> Due to its importance in mitosis, the molecular components and dynamics of the mitotic [[Cell cortex|actomyosin cortex]] is an area of active research.