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Copyright © 2009 JCBNSummary In this study, we investigated the mechanistic role of the caspase cascade in extrinsic and intrinsic apoptosis induced by apigenin, which has been targeted as a candidate in the development of noncytotoxic anticancer medicines. Treatment with apigenin (1–100 µM) significantly inhibited the proliferation of MDA-MB-453 human breast cancer cells in a dose-and time-dependent manner with IC50 values of 59.44 and 35.15 µM at 24 and 72 h, respec-tively. This inhibition resulted in the induction of apoptosis and the release of cytochrome c in cells exposed to apigenin at its 72 h IC50. Subsequently, caspase-9, which acts in mitochondria-mediated apoptosis, was cleaved by apigenin. In addition, apigenin activated caspase-3, which functions downstream of caspase-9. The apigenin-induced activation of caspase-3 was accom-panied by the cleavage of capases-6,-7, and-8. These results are supported by evidence showing that the activity patterns of caspases-3,-8, and-9 were similar. The present study supports the hypothesis that apigenin-induced apoptosis involves the activation of both the intrinsic and extrinsic apoptotic pathways. Key Words: apigenin, apoptosis, caspases cascade, human breast cancer MDA-MB-453 cell