During stroke, the level of the protein-conjugated acrolein (PC-Acro) in plasma increased, and the multiplied value of PC-Acro and polyamine oxidases (PAO; acrolein-producing enzymes consisting of spermine oxidase (SMOX) and acetylpolyamine oxidase (PAOX)) was nearly parallel with the size of brain infarction [9]. Here, SMOX is linked to brain infarction.