The FRT stop cassette has been excised, allowing the ubiquitin promoter to drive expression of a fusion protein composed of a transmembrane domain (Tag:M(mCd8a)), a DQVD caspase cleavage sequence, and QF2. This protein is designed to act as a caspase-inducible form of QF2. In the absence of caspase, the transmembrane domain tethers QF2 to the plasma membrane, rendering it inactive. In the presence of caspase, the fusion protein is cleaved at the DQVD site, releasing the QF2 coding region so that in can enter the nucleus and drive transcription.