The function of ARHGEF12 (Rho guanine nucleotide exchange factor 12, Ensembl gene identifier ENSG00000196914) is as follows. Acts as guanine nucleotide exchange factor (GEF) for RhoA GTPase and may act as GTPase-activating protein (GAP) for GNA12 and GNA13 (PubMed:11094164). May play a role in the regulation of RhoA GTPase by guanine nucleotide-binding alpha-12 (GNA12) and alpha-13 (GNA13) (PubMed:11094164). Promotes endothelial cell and actin stress fiber reorientation in response to mechanotransduction (By similarity). .