UAS regulatory sequences drive expression of a chimeric protein in which the Pvr extracellular ligand-binding domain has been replaced by the dimerization domain of the bacteriophage λ cI repressor (to induce constitutive dimerization of the encoded protein). A Tag:MYC epitope has been inserted at the junction of the λ and Pvr sequences. In addition, a N1134A amino acid replacement has been introduced into the Pvr intracellular domain (this results in a kinase-dead protein).