Transgenic construct used to investigate the possible role of z protein in long-range interactions between enhancers and promoters. Contains an FRT cassette containing the w eye enhancer (-1180 to -1450bp relative to the transcription start site), a loxP cassette containing a truncated gypsy\su(Hw)BR insulator (contains only 5 su(Hw) binding sites), and the w+mC mini-gene. The z protein binding sites in the w upstream promoter region have been removed.