EGFP is a stable protein (t_1/2 >24 h) frequently used as a marker for gene expression, cell lineage or as an in situ tag for fusion proteins. A shortened half-life would be beneficial in accurately measuring the kinetics of transient mRNA transcription from regulated promoters. We created destabilized EGFP variants by introduction of destabilizing N-terminal amino acid residues. The decay of EGFP variants was quantified by FACS analysis of cells with blocked translation or blocked transcription and half-lives of between 0.33 h to 1.86 h were determined for the variant proteins.