title: GEFs on the RhoAd to a colossal nucleus.
abstract: Cytokinesis in normal cell division requires RhoA-regulated actomyosin contraction of the cleavage furrow; this process is aborted in megakaryocyte endomitosis, leading to polyploidy. In this issue of Developmental Cell, Gao et al. (2012) trace the basis of endomitosis to sequential downregulation of guanine nucleotide exchange factors GEF-H1 and ECT2.
authors.affiliation: Dana-Farber Cancer Institute, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02215, USA. ramesh_shivdasani@dfci.harvard.edu
authors.forename: Ramesh A
authors.initials: RA
authors.lastname: Shivdasani