Injection of activated protein C (APC) is the last resort to rescue a patient with severe sepsis. Research into how APC works reveals that the drug inactivates histones (pages 1318–1321), which are toxic during severe sepsis. Histones are not generally considered to be noxious; after all, they form the core around which DNA is wrapped in eukaryotes. Not only do these proteins have this essential architectural role, but also their modification is one of the key mechanisms for gene regulation.