UASt sequences drive expression of "SCAT3", a genetically encoded reporter for caspase activation. SCAT3 comprises the ECFP and Venus proteins linked by an 18 amino acid peptide that includes DEVD, the caspase-3 cleavage sequence. Caspase activation can be monitored by changes in the fluorescence energy transfer (FRET) from ECFP to Venus; cleavage of the linker peptide by activated caspase abolishes the FRET (details from PMID:12527749).