Transgenic construct used to study the Mcp boundary element. Consists of the y wing and body enhancers, a loxP cassette containing a 508bp sub-fragment of the Mcp boundary element (contains the 138bp silencer) of Abd-B, the y gene (including the bristle enhancer) and a mini-w gene. The Mcp element is oriented such that the silencer is proximal to the y wing and body enhancers.