Thioredoxin-disulfide reductases (TrxR) catalyze the reduction of thioredoxin (Trx) using NADPH as a reducing agent. These 3 components comprise the thioredoxin system. The system is ubiquitous from Archea to man and supports several processes crucial for cell function, cell proliferation, antioxidant defense and redox-regulated signaling cascades. There are numerous systems with thiol-dependent redox mechanisms, which are related to important pathological states and human diseases. Thioredoxin reductase is upregulated in several types of cancer, including malignant mesothelioma, thus it is a good target for anti-tumor therapy.