HEK-293T telomerase over-expressing cell pellets express ~400-fold greater telomerase activity over endogenous levels. These HEK-293T cells have been transiently transfected with plasmid DNA encoding hTERT, hTR, and dyskerin, leading to ~400-fold higher enzymatic activity. In this figure, cell aliquots were removed over time for analysis of their telomerase activity using a direct activity assay. Lane E: untransfected, endogenous activity – arrows indicate the first three telomeric repeats. Lanes 3 - 7: activity at days 3 – 7 post-transfection.