Two copies of a modified eve stripe 2 enhancer (in which all gt protein binding sites have been deleted and the three low affinity bcd protein binding sites have been changed to the consensus bcd protein binding site) are fused upstream of an eve fragment containing the basal promoter and 80bp of leader sequence. These eve sequences are separated from a wild-type gt cDNA by an FRT cassette containing a transcriptional stop sequence. The eve 3' UTR is fused downstream of the gt cDNA sequence.