Schematic diagram of lentiviral vector encoding hTERT. The human telomerase reverse transcriptase (hTERT) sequence was inserted into the TRIP.ΔU3.BR.IRES green fluorescent protein (GFP) lentiviral vector between the BamHI and EcoRI cloning sites. The ensuing bi-cistronic construct contains the full-length hTERT coding sequence under the control of the human cytomegalovirus immediate early promoter (CMVie), followed by the encephalomyocarditis virus internal ribosome entry site (IRES) and the enhanced green fluorescence protein (EGFP). LTR indicates long terminal repeat; cPPT, central polypurine tract; and CTS, central termination sequence.