Transgenic construct used to study mechanisms involved in long-range enhancer-promoter interactions. Contains divergently transcribed w and lacZ reporters. A 1.6kb BamHI-BglII IAB8 enhancer fragment, an FRT cassette (containing a 1.7kb fragment which includes Fab-8 insulator and Abd-B promoter targeting sequence (PTS) sequences) and a defective IAB7 enhancer (with mutations in the Kr protein binding sites) is fused downstream of the lacZ transcription unit.