Aim To investigate the apoptosis-inducing effects of AgLA2 on lung carcinoma cells SPC-A-1 and its mechanism in vitro.Methods The MTT assay was used to assess the proliferation of SPC-A-1 cells treated with AgLA2 in vitro.Apoptosis-inducing effects was investigated by DNA agarose gel electrophoresis,cell morphology and Elisa.RT-PCR was used to measure the expression of bcl-2 and bax mRNA,and immunocytochemistry was used to measure the expression of bcl-2 and bax protein.Results The IC50 of AgLA2 to SPC-A-1 cells was(3.447?0.436)mg?L-1.Treated with AgLA2,typical nuclear chromatine condensation and fragmentation were observed.The concentration of Caspase-3 in the group treated with AgLA2 was higher than that of the control group.Treated with AgLA2,bcl-2 mRNA,protein expression decreased while bax mRNA,protein expression increased.Conclusions AgLA2 can inhibit proliferation and induce apoptosis of SPC-A-1 cells.Its mechanism of action may be related to changing the ratio of bax/bcl-2 and the set-point of apoptosis,making the apoptosis power hold dominance.