Probably functions as a GTPase-activating protein (GAP) for RAC1 and/or CDC42. Required for optic stalk formation. Ubiquitously expressed. Expressed at all developmental stages, with highest expression at the posterior pole of the early cellular blastoderm, the neuro-ectoderm prior to neuroblast delamination, rows of epidermal cells in the most posterior part of thoracic and first abdominal segments and a ring of epidermal cells at the posterior end of the embryo.