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) (nucleotides 64292 to 64916 in clone DS07696) in the reverse orientation, the y coding region, a loxP cassette containing Abd-B-PTS in the reverse orientation and the mini-w gene.