Acts as a GTPase-activating protein (GAP) for ARL2 with low specific activity. Also present in the cuticular plate of auditory hair cells. In the organ of Corti, in inner hair cells, expressed along the length of the stereocilia, but excluded from the very tip. Colocalizes with F-actin cytoskeleton. Expressed in the cochlea and in the organ of Corti, as well as in the supporting cells, including pillar and Dieters' cells (at protein level). At P02, in the organ of Corti, expressed in the stereocilia of outer hair cells and in the kinocilia of both outer and inner hair cells. Also concentrated at the cuticular plate level of auditory hair cells. However, before P07, expression in the inner hair cell stereocilia is very weak. By P07, in auditory hair cells, patchy expression detected along the length of stereocilia, but absent from the very tip. Later in development, detected in the stereocilia bundles and microvilli of sensory cells and also in the supporting cell bodies (at protein level).