Rho GTPase-activating protein involved in the signal transduction pathway that regulates endothelial cell capillary tube formation during angiogenesis. Acts as a GTPase activator for the RAC1 by converting it to an inactive GDP-bound state. Inhibits RAC1- dependent lamellipodia formation. May also play a role in transcription regulation via its interaction with VEZF1, by regulating activity of the endothelin-1 (EDN1) promoter (By similarity). . This is the function of ENSG00000128805 (ARHGAP22, Rho GTPase activating protein 22).