UASt sequences regulate expression of Delta in which the extracellular domain has been replaced in its entirety by Tag:LIG(FSHb) and the intracellular domain has been replaced by an unrelated 38 amino acid peptide (GSWIPSFYNVVTGKTLALPNLIALQHIPLSPAGVIAKRPAPIALPNSCAA) bearing two Lys residues that direct the ligand to the Epsin pathway. The coding sequence is tagged with HRP immediately upstream of the Delta transmembrane domain. A single FRT site is present in between the UASt and coding sequences.