The RMCE cassette of the Mi{MIC}Dscam4MI01598 insertion has been replaced with a splice acceptor followed by a cassette sequence flanked by FRT sites fused to the remainder of the Dscam4 coding sequence, followed by 2A-lexA::p65. In the absence of FLP, translation of Dscam4 ends with no reporter produced; where FLP is present, the FRT-cassette is excised and lexA::p65 is produced.