“Treating with methylglyoxal …-(guanylhydrazone), MGBG , an irreversible inhibitor of S-adenosylmethionine decarboxylase, which is a key enzyme in spermidine … spermine biosynthesis, and therefore used to deplete cellular polyamines, prevented the protective effect of L-cysteine and L-methionine, but the addition of exogenous polyamines inhibited the influence of MGBG.”