Our results suggest that the Bcl-2 expression was decreased while the Bax expression was significantly increased, which was associated with the loss of ΔΨm and release of cytochrome c. In addition, the SAMC treatment of human breast cancer cell lines MCF-7 and MDA-MB-231 resulted in the activation of caspase-9 and caspas-3/7 as well as the increase of PARP, which lead to the intrinsic apoptosis. The gene discussed is CYCS; the disease is breast carcinoma.