Ubi-p63E regulatory sequences drive expression of a caspase-inducible form of lexA::p65. The construct encodes a fusion protein consisting of Mmus\Cd8a and the lexA::p65 coding region, separated by the caspase-3-binding and cleavage domain of Diap1 (amino acid residues 2-147, with residues 21 and 22 mutated from NN to GV, in order to protect the cleaved product from possible N-end rule degradation). In the absence of caspase, the Mmus\Cd8a sequence tethers lexA::p65 to the plasma membrane, rendering it inactive. In the presence of caspase, the fusion protein is cleaved at the DQVD site in the Diap1 sequence, releasing the lexA::p65 coding region so that in can enter the nucleus and drive transcription.