Cytochrome c has been shown to play an important role in apoptosis. The protein is located in the space between the inner and outer mitochondrial membranes. An apoptotic stimulus triggers the release of cytochrome c from the mitochondria into the cytosol where it binds to Apaf-1. The cytochrome c/Apaf-1 complex activates caspase-9 which then activates caspase-3 and other downstream caspases of the apoptotic cascade. The PromoKine Cytochrome c Apoptosis Detection Kit provides an effective means for detecting cytochrome c translocation from mitochondria into cytosol during apoptosis. The kit provides an easy-to-use procedure and unique reagents for separating a highly enriched mitochondria fraction from cytosol. Cytochrome c released from mitochondria into cytosol is then determined by Western blotting using the cytochrome c antibody provided in the kit. The procedure is very simple and straightforward – no ultracentrifugation is required and no toxic chemicals are involved.