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Ras homology family A (RhoA)-like includes RhoA, RhoB and RhoC The RhoA subfamily consists of RhoA, RhoB, and RhoC. RhoA promotes the formation of stress fibers and focal adhesions, regulating cell shape, attachment, and motility. RhoA can bind to multiple effector proteins, thereby triggering different downstream responses. In many cell types, RhoA mediates local assembly of the contractile ring, which is necessary for cytokinesis. RhoA is vital for muscle contraction; in vascular smooth muscle cells, RhoA plays a key role in cell contraction, differentiation, migration, and proliferation. RhoA activities appear to be elaborately regulated in a time- and space-dependent manner to control cytoskeletal changes. Most Rho proteins contain a lipid modification site at the C-terminus, with a typical sequence motif CaaX, where a = an aliphatic amino acid and X = any amino acid. Lipid binding is essential for membrane attachment, a key feature of most Rho proteins. RhoA and RhoC are observed only in geranylgeranylated forms; however, RhoB can be present in palmitoylated, farnesylated, and geranylgeranylated forms. RhoA and RhoC are highly relevant for tumor progression and invasiveness; however, RhoB has recently been suggested to be a tumor suppressor. Due to the presence of truncated sequences in this CD, the lipid modification site is not available for annotation.
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