The Ubi-p63E promoter drives expression of a sensor of caspase activity. The sensor is a fusion protein comprised of a transmembrane domain (Tag:M(mCd8a)), amino acids 2-147 of Diap1 and the GAL4 driver. The Diap1 sequence includes a caspase cleavage site, DQVDGV (this site has been mutated from the original DQVDNN to prevent degradation of the cleaved product by the N-end rule pathway) and also contains the D135R mutation (to prevent caspase inhibition by the biosensor). In the absence of caspase activity, the transmembrane domain tethers the fusion protein to the membrane. Upon cleavage of the DQVDGV site by active caspase, the GAL4 driver is released, allowing it to enter the nucleus and drive expression of UAS-driven responder transgenes. Three copies of the Tag:MYC tag are present at the C-terminal end of the GAL4 sequence.