Geraniin, a form of tannin separated from geranium, causes cell death through induction of apoptosis. Geraniin triggered cell death by caspase-3-mediated cleavage of FAK and was associated with the up-regulation of Fas ligand expression, the activation of caspase-8, the cleavage of Bid, and the induction of cytochrome c release from mitochondria to the cytosol in human melanoma cells (Lee et al, 2008).
Lee JC, Tsai CY, Kao JY, Kao MC, et al. Geraniin-mediated apoptosis by cleavage of focal adhesion kinase through up-regulation of Fas ligand expression in human melanoma cells. Mol Nutr Food Res. 2008 Jun;52(6):655-63.