['To observe the apoptosis induced by exogenous NO in Tca8113 cells and to investigate the possible mechanism.', 'SNP as NO donor was used to treat the tongue squamous cell carcinoma Tca8113 cells. Cytotoxic and apoptotic effects of NO on Tca8113 cells were examined by using MTT assay, acridine orange (AO) staining, Wright-Giemsa staining, agarose gel electrophoresis and flow cytometry. Western blot was performed for investigating the apoptotic mechanism.', 'NO had a remarkable proliferation inhibiting effect on Tca8113 cells. After being exposed to exogenous NO, Tca8113 cells showed series of apoptotic morphological changes such as cell shrinkage, nuclear condensation; and also showed DNA fragmentation, G2/M phase arrest as well as upregulation of the tumor suppressor P53 protein.'] Does [ Apoptosis induce by exogenous nitric oxide in Tca8113 cells ]?