Rho GTPases play a fundamental role in numerous cellular processes that are initiated by extracellular stimuli that work through G protein-coupled receptors. This gene encodes a protein that functions as a specific guanine nucleotide exchange factor for RhoA. It also interacts with ephrin A4 in vascular smooth muscle cells. Two alternatively spliced transcripts variants that encode the same protein have been found for this gene. [provided by RefSeq, Aug 2010].