P{TransTimerLex} is an enhancer trap construct that can be used to detect expression dynamics when crossed to a lexAop-driven reporter and can also be used to manipulate gene expression in labelled cells. The enhancer trap sequence consists of the Drosophila synthetic core promoter (DSCP) promoter followed by a multicistronic transcription unit in which a destabilized form of sfGFP (sfGFP that is tagged at C-terminal end with the Tag:PEST(mOdc) destabilization sequence) is separated from the 'LHG' lexA::GAD driver by a self-cleaving 2A motif. The destabilized sfGFP protein is also tagged at the N-terminal end with a Tag:NLS(SV40-largeT) nuclear localization signal and at the C-terminal end with 3xTag:MYC. The transgene contains a number of translation enhancing elements: a short 87 bp intervening sequence (IVS) from Mhc to promote mRNA export to the cytoplasm, a 21bp synthetic AT-rich sequence (Syn21) to promote translational initiation and an efficient p10 polyadenylation signal.