UAS regulatory sequences drive expression of the 'FlipGFP' fluorogenic reporter of caspase activity. The FlipGFP reporter consists of two open reading frames (ORF) separated by a T2A sequence, which allows each ORF to be translated as a separate protein. Each ORF encodes a split-GFP fragment; one split-GFP fragment (β1-9) encodes the first 9 β strands and central α-helix of GFP, the second split-GFP fragment consists of β strand 10 followed by β strand 11 flanked by heterodimerizing coiled coils E5 and K5, with in addition, the Caspase-3/7 cleavage sequence DEVDG (an additional Gly residue is added before the cleavage sequence as a flexible linker) inserted in between β strand 11 and K5. The presence of the E5 and K5 coils "flips" the β11 strand, so that the β 10 and 11 strands form a parallel structure (instead of the normal anti-parallel organization), preventing the formation of a functional fluorophore. Upon protease cleavage, β11 can form an anti-parallel structure with the β10 strand, which enables self-assembly with the β1-9 split-GFP fragment, reconstituting a functional fluorescent protein.