Mitochondria are not only the powerhouse of the cell, but are also involved in cellular suicide via apoptosis (programmed cell death). The mitochondrial apoptotic pathway is a major regulator in mammalian cells death, where pro- and anti-survival Bcl-2 proteins meet at the mitochondrial outer membrane and tightly regulate the fate of a cell. Treatment-resistant tumour cells often possess mitochondria which are enriched in the pro-survival Bcl-2 membrane protein which blocks any apoptotic signals upon onset via oxidative stress. Our main aim is to generate by using neutron reflectometry fundamental knowledge about the membrane mediated function of the cell-death causing (anti-survival) Bax protein and its counterplayer, the pro-survival Bcl-2 membrane protein to regulate and execute apoptosis; information also useful for novel cancer strategies.