TKT and neoplasm: Our results indicate that transfection of the enhanced pGL3-basic-hTERTp-TK-EGFP-CMV with GCV treatment significantly inhibits the survival rate of nasopharyngeal carcinoma 5-8F cells and the progress of nasopharyngeal xenograft in nude mice, and the enhanced pGL3-basic-hTERTp-TK-EGFP-CMV/GCV has much better tumor killing efficacy than pGL3-basic-hTERTp-TK-EGFP/GCV in both NPC 5-8F and MCF-7 cells.