Transgenic construct used to investigate the properties of endogenous (non-gypsy) su(Hw) binding sites in an enhancer blocking assay. Contains a y reporter gene, into which a loxP cassette has been inserted at -900 relative to the transcription start site, downstream of the wing and body enhancers. The cassette contains a 424bp region from cytological position 62D that includes four predicted su(Hw) binding sites in the reverse orientation, 2 2kb of γbacteriophage DNA and the gypsy element.