A 1.0kb EcoRI fragment (+143 to +144 of the BXC region, coordinates according to FBrf0042053) which covers the deletion found in the Abd-Biab7-R73 allele is fused upstream of the Ubx promoter driving lacZ.
Expression is observed in the mesoderm and ectoderm of parasegments 12--14, and in the posterior part of the developing gonad at later stages.