Transgenic construct used to study a Polycomb response element (PRE). It consists of 1. an FRT cassette that contains both a Rnor\Cd2αTub84B.PC marker and the 1.6kb bxd PRE, 2. a reporter in which the Ubx early enhancer (EE), imaginal disc (DE) enhancer and promoter are fused upstream of lacZ, and 3. a y+t* marker.