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in which the extracellular domain has been replaced in its entirety by Tag:LIG(FSHb) and the intracellular domain has been replaced by six copies of a mutated Tag:MYC epitope (the K residue in all six copies of the epitope has been mutated to R and the LI dipeptide that comprises a clathrin internalization signal that bypasses the requirement for Epsin has been mutated in all 6 copies). 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.