Apoptotic cell death is essential for development, immune function or tissue homeostasis, and it is often deregulated in disease. Mitochondrial outer membrane permeabilization (MOMP) is central for apoptosis execution and plays a key role in its inflammatory outcome. Knowing the architecture of the macromolecular machineries mediating MOMP is crucial for understanding their function and for the clinical use of apoptosis. Our recent work reveals that Bax dimers form distinct line, arc and ring assemblies at specific apoptotic foci to mediate MOMP. However, the molecular structure and mechanisms controlling the spatiotemporal formation and range of action of the apoptotic foci are missing. Although it is widely accepted that Bax and Bak function and molecular mechanism at apoptotic foci largely overlap, there is limited evidence how Bak works. Here I present our latest discoveries in the molecular similitudes and differences between Bax and Bak in apoptosis.