UASt regulatory sequences drive expression of the full-length Xbp1 transcription unit (includes the 5' UTR, coding sequence and intron, 3' UTR and 0.55kb immediately downstream of the 3'UTR). Sequence encoding Venus and Akaluc has been inserted at the C-terminal end of the coding region. The Venus and Akaluc tags only become in frame with the Xbp1(s) coding sequence after splicing using the unconventional splice site (this occurs under stress conditions).