CASP3 and cancer: Amongst all these protein-SNOs, the most prominent is caspase-3, which cannot be denitrosylated by GSH or GSNOR, but exclusively by Trx; this proves the S-nitrosylation of this apoptotic protein by NO donors, but the failure of the activity regeneration in the absence of Trx, which again establishes a link between caspases and cancer and eliminates the direct role of GSH in the same, while indirectly GSH as well as reduced human Trxs have the potential to denitrosylated S-nitroso thioredoxins, inactivating caspase-3, linking GSH to the apoptotic pathways [12,58].