Objective:To investigate the inhibitory effect of monoclonal antibody(McAb) NJ488-1 on the lung adenocarcinoma cell line SPC-A1 in vivo and in vivo. Methods:SPC-A1 cells were plated on a soft agar matrix and treated with McAb NJ488-1 (0, 200, 400, 800, 1600, 2000 μg/ml). After 2 weeks’ incubation, the colony formation efficiency and the inhibition ratio of colonies were calculated. Xenograft was established by subcutaneous injection of SPC-A1 cells and antibodies were administered intraperitoneally at three different doses (200, 400, 800 μg per mouse). Animals were monitored by tumor size. Three weeks after the initiation of treatment, tumors were removed and weighed, and tumor growth inhibition was calculated. SPC-A1 cells were cultured with or without 400 μg/ml McAb for 24 h or 48 h. The morphology changes of cells were observed and the apoptosis rates were measured by flow cytometry. Results:In soft agar assay, the colony formation efficiency in McAb groups reduced in a dose-dependent manner. The higher level of antibody inhibited colony formation compared to the lower one, with 62.5% inhibition ratio at 400 μg/ml vs 23.4% at 200 μg/ml. When the concentration of McAb was 800 μg/ml or even higher, the inhibition ratio was up to 100%. McAb caused varying degrees of decrease in tumor volume compared with control mice(P = 0.004, P = 0.003, 400 μg and 800 μg McAb group vs control). In the 200, 400, 800 μg McAb groups, tumor growth inhibition was 10.44%, 37.29% and 44.04%, respectively. The average tumor weights of the 400, 800 μg McAb group and the control group, the 200 μg McAb group and 800 μg McAb group were significantly different(P = 0.032, P = 0.015, P = 0.048, respectively). NJ488-1 led to the obvious cyto-morphology changes and significantly induced the apoptosis of SPC-A1 cells in a time-dependent manner(P < 0.001). Conclusion:The McAb NJ488-1 inhibited the growth of lung adenocarcinoma cell line both in vitro and in vitvo. It is suggested that cell apoptosis induced by NJ488-1 might be the mechanism of the anti-tumor activity.