Insertion of "T2A-Gal4-STOP-3P3-RFP", containing the GAL4 coding sequence and a 3P3-RFP marker flanked by loxP sites, into Srr in-frame. (Region 3R:9367596..9367646 (FB2018_02) has been replaced.) This results in GAL4 being expressed under the control of Srr regulatory sequences, with the Srr coding region intact.