Rho GTPases alternate between an inactive GDP-bound state and an active GTP-bound state, and GEFs facilitate GDP/GTP exchange. This gene encodes a guanine nucleotide exchange factor (GEF) which interacts with Rho GTPases involved in contraction of vascular smooth muscles, regulation of responses to angiotensin II and lens cell differentiation. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jan 2012].