The mtrm promoter is fused upstream of wild-type bcd coding sequence (from cDNA) that is tagged at the N-terminal end with EGFP. An FRT cassette that contains 1. the bcd 3'UTR and 2. a Disc\RFP3xP3.cUa marker is present downstream of the bcd coding sequence (the presence of the bcd 3'UTR results in the EGFP-tagged protein being expressed in a graded distribution along the anterior-posterior axis of the embryo). Sequence encoding the sqh 3'UTR is present downstream of the FRT cassette.