A control transgene in which a sequence cassette encoding a fusion protein composed of 1. a Tag:HA epitope, 2. the complete Cirl extracellular region, including the autoproteolytically active GAIN domain, but with a mutation in the GPCR proteolysis site (GPS) that prevents cleavage, 3. the juxta- and transmembrane segment of N (JTS), 4. the lexA::VP16 driver and 5. three copies of the Tag:V5 epitope has been inserted into the attP site in TI{TI}Cirl^KO.attP.w-, resulting in expression of the fusion protein under the control of endogenous Cirl regulatory sequences. The mutation in the GPS site prevents release of the lexA::VP16 driver upon activation of Cirl.