Alternatively, aldehyde dehydrogenases catalyze the oxidation of HNE to form 4-hydroxy-2-nonenoic acid (HNEA). Cytochrome P450 can also contribute to the clearance of reactive aldehydes [27,28]. At low levels, α,β-unsaturated aldehydes are oxidized by mammalian P450 enzymes to their carboxylic acid derivatives [27]. Additionally, P450 has been shown to catalyze the reduction of α,β-unsaturated aldehydes to their alcohol form in vivo [28]. Thus, redundantmechanisms for the detoxification and clearance of reactive lipid electrophiles exist to efficiently scavenge such reactive species and prevent cytotoxicity