The permeabilization of mitochondrial outer membrane and the subsequent release of cytochrome c and other apoptogenic proteins from mitochondrial intermembrane space into the cytoplasm is considered a hallmark of many apoptotic pathways. Therefore assaying these proteins in mitochondrial and cytoplasmic fractions is of prime interest for many researchers.

MSA12 is a Western blot antibody cocktail that allows for the detection of cytochrome c in cytoplasmic and mitochondria-containing fractions for determining the proportion of released cytochrome c from mitochondria to the cytoplasm from apoptosis. The kit also includes antibodies against a cytoplasmic protein marker, glyceraldehyde-3-phosphodehydrogenase (GAPDH), and 2 mitochondrial markers, pyruvate dehydrogenase subunit E1-alpha (a matrix marker), and ATP synthase subunit alpha (an inner membrane marker). This set of control markers allows for the monitoring and/or optimization of the permeabilization conditions.