lacZ reporter expression is governed by the Ubx proximal promoter (-3.1kb to +1kb) in combination with the a BamHI-PstI subfragment of the 3101 genomic fragment.
In embryos, from stage 7, expressed in even-numbered parasegments 6-12; expression highest in anterior portion of each parasegment, with a sharp border at the parasegment boundary; expression strong in ectoderm, weak in mesoderm.