Anthrax toxin lethal factor complex. Computer model showing the structure of anthrax lethal factor (magenta) complexed with a peptide from mitogen-activated protein kinase 2 (MAPKK, cyan). This enzyme is one of three protein components that form the anthrax toxin produced by the bacterium Bacillus anthracis. Lethal factor (LF) disrupts cellular signalling pathways in an infected cell, eventually leading to cell death.