Objective: To investigate the feasibility of marking the human tumor cells with enhanced green fluorescent protein (EGFP) in vitro. Methods: The retroviral vector LGSNencoding EGFP was constructed and three human tumor cell lines were infected with LGSN amphotropic virus.Tumor cell lines that stably express EGFP were selectedwith G418. The integration and expression of EGFP gene were analyzed by polymerase chain reaction, and flowcytometry (FCM). Results: After gene transfection andping-pong transduction, amphotropic producer lineAm12/LGSN was generated with a stable greenfluorescence signal readily detectable by FCM in up to 97% of examined cells. The viral titer in the supernatants was up to 8.2105CFU/ml. After transduction and selection,G418-resistant leukemia K562, mammary carcinomaMCF-7, and bladder cancer 5637 cells were developed, inwhich the integration of both EGFP and neomycinresistance gene was confirmed by DNA amplification. In comparison with uninfected cells, FCM analysis revealedEGFP expression in up to 90% (range 85.5%~90.0%) oftumor cells containing LGSN provirus. Conclusion: Theretroviral vector LGSN can effectively mark the humantumor cells with a stably EGFP expression which may be in studying tumor growth, metastasis and angiogenesis. Objective: To investigate the feasibility of marking the human tumor cells with enhanced green fluorescent protein (EGFP) in vitro. Methods: The retroviral vector LGSNcoding EGFP was constructed and three human tumor cell lines were infected with LGSN amphotropic virus. Tumor cell lines that stably express EGFP were selected with G418. The integration and expression of EGFP gene were analyzed by polymerase chain reaction, and flowcytometry (FCM). Results: After gene transfection and ping-pong transduction, amphotropic producer line Am12 / LGSN was generated with a stable green fluorescence signal signal detectable by FCM in up to 97% of the examined cells. The viral titer in the supernatants was up to 8.2105 CFU / ml. After transduction and selection, G418-resistant leukemia K562, mammary carcinomaMCF-7, and bladder cancer 5637 cells were developed, inwhich the integration of both EGFP and neomycinresistance gene was confirmed by DNA amplification. In comparisonCompare uninfected cells, FCM analysis There is evidence that the expression of EGFP expression in up to 90% (range 85.5% -90.0%) of the tumor cells containing LGSN provirus. Conclusion: There is evidence that the tumor cells with a stably EGFP expression may be in studying tumor growth, metastasis and angiogenesis.