Guanine nucleotide exchange factor for ARF6. In interphase associated with the plasma membrane, in particular with membrane ruffling regions. Ubiquitously expressed, with highest levels in liver. Present in brain, with highest levels in olfactory bulb, cortex, hippocampal pyramidal cell layer and cerebellar granule cell layer (at protein level). Expressed only in spinal cord at 13 dpc. At 18 dpc and P0, appears weakly in forebrain. Expression in brain increases after birth and peaks at P10.