twi genomic fragment that includes the proximal enhancer, promoter and transcription unit (including 5'UTR and 3'UTR). 32 repeats of the SunTag(v4) peptide have been inserted at the N-terminal end of the coding sequence (this allows visualization of the protein). 128 copies of the Tag:MS2 stem loop have been inserted at the N-terminal end of the 3'UTR (this allows visualization of the transcript).