A sequence cassette encoding a T2A peptide, a nuclear localization signal and the p65(AD)::Zip+ hemidriver has been inserted into the endogenous pb locus, at the C-terminal end of the coding sequence. This allows expression of the p65(AD)::Zip+ hemidriver under the control of endogenous pb regulatory sequences, and the presence of the T2A sequence promotes separate translation of the pb and p65(AD)::Zip+ proteins.