Transgenic construct used to study interactions between insulator sequences. Consists of 10 UAS sites, an FRT cassette containing four copies of the third su(Hw) binding site from the gypsy insulator (gypsy\su(Hw)BR) followed by four consensus binding sites for CTCF, the y transcription unit, a loxP cassette containing four copies of the third su(Hw) binding site from the gypsy insulator followed by four consensus binding sites for CTCF and the mini-w gene.