Cysteine and serine proteases are prominent players in the
control of developmental and pathogen-activated cell deaths in
plants. Ethylene, salicylic acid, the small G-protein Rac,
calcium and reactive oxygen species are recurring mediators of
death signaling. Lastly, the mitochondrion has emerged in both
plant and animal systems as a ‘central depot’ that interprets
multiple signals and in some instances determines the fate of
the cell.