Figure 1. Scheme illustrates de novo synthesis of polyamines from ornithine. ODC, ornithine decarboxylase; dcAdoMet, decarboxylated s-adenosyl-L-methionine; SPDSY, spermidine synthase; SPMSY, spermine synthase; MTA PAO, polyamine oxidase; SSAT, spermidine/spermine N(1) acetyltransferase; SMO, spermine oxidase.