Part of signaling pathway that is required for completion of cytokinesis. gapA and rgaA control cortexillin localization to the cleavage furrow and hence may be involved in cleavage of the midbody in the final stage of cytokinesis by regulating the actin cytoskeleton. Forms a complex by linking activated rac1A to ctxA. Assembly of this complex is necessary for the recruitment of cortexillin to the midzone of a dividing cell. Overexpression leads to the suppression of the formation of cellular projections containing F-actin and to a defect in cytokinesis. Heterotetramer. Quaternary complex with activated rac1A, ctxA and ctxB. Interacts directly with rac1A and ctxA. Preferentially interacts with activated forms of rac1A, rac1B and rac1C. Interacts with racE. Enriched in the cortex of interphase cells and translocated to the cleavage furrow during cytokinesis. No change in cytokinesis as gapA can functionally replace this protein. Null cells project numerous filopodia, show increased cell motility during growth and form multi-tipped aggregates during development and show elevated levels of F-actin that is organized in large leading edges, membrane ruffles or numerous large filopods. RgaA and gapA double mutant prevents quaternary complex formation (activated rac1A, ctxA, ctxB and either rgaA or gapA) and localization of the cortexillins to the cleavage furrow; interferes with cytokinesis to a similar extent as the simultaneous elimination of ctxA and ctxB, shows extremely large, flat and multinucleate cells and has increased cell motility and abnormal development. rgaA lacks rasGAP activity in vitro. rgaA expression is inversely correlated with the speed of cell motility.