biostudies-literatureUnknown22(20)Maeda MRho GTPases are molecular switches that transmit biochemical signals in response to extracellular stimuli to elicit changes in the actin cytoskeleton. Rho GTPases cycle between an active, GTP-bound state and an inactive, GDP-bound state. These states are regulated by two distinct families of proteins-guanine nucleotide exchange factors and GTPase-activating proteins (GAPs). We studied the role of a previously uncharacterized GAP, ARHGAP18 (MacGAP). Overexpression of ARHGAP18 suppressed the activity of RhoA and disrupted stress fiber formation. Conversely, silencing of ARHGAP18 by small interfering RNA transfection-enhanced stress fiber formation and induced rounding of cells. We examined the role of ARHGAP18 in cell spreading and migration. Immunofluorescence analysis revealed that ARHGAP1Molecular biology of the cell3840-52https://www.ebi.ac.uk/biostudies/studies/S-EPMC3192863biostudies-literatureARHGAP18, a GTPase-activating protein for RhoA, controls cell shape, spreading, and motility.PMC3192863Shimokata KHasegawa HSenga TAsano EYuang HHyodo TIto SHasegawa YFunasaka KHamaguchi MMaeda MfalseARHGAP18, a GTPase-activating protein for RhoA, controls cell shape, spreading, and motility.Rho GTPases are molecular switches that transmit biochemical signals in response to extracellular stimuli to elicit changes in the actin cytoskeleton. Rho GTPases cycle between an active, GTP-bound state and an inactive, GDP-bound state. These states are regulated by two distinct families of proteins-guanine nucleotide exchange factors and GTPase-activating proteins (GAPs). We studied the role of a previously uncharacterized GAP, ARHGAP18 (MacGAP). Overexpression of ARHGAP18 suppressed the activity of RhoA and disrupted stress fiber formation. Conversely, silencing of ARHGAP18 by small interfering RNA transfection-enhanced stress fiber formation and induced rounding of cells. We examined the role of ARHGAP18 in cell spreading and migration. Immunofluorescence analysis revealed that ARHGAP12011-01-01T00:00:00Z2011 Oct2025-04-04T07:24:43.534Z2019-03-27T00:44:56ZS-EPMC31928632186559510.1091/mbc.E11-04-0364