Transgenic construct used to study interactions between insulators and promoters. Consists of 10 UAS sites, an FRT cassette containing the Abd-B promoter targeting sequences (Abd-B-PTS) and Fab-8 insulator (nucleotides 63683 to 64582 in clone DS07696) in the reverse orientation, the y coding region, a loxP cassette containing a 370bp DNA fragment from the Abd-B A promoter (which contains a CTCF binding site) and the mini-w gene.