TXN and systemic sclerosis: We analyzed the mRNA expression levels of nrf2 and its main target genes involved in the regulation of ROS production [heme oxygenase-1 (HO-1), glutamate cysteine ligase (GCL), and thioredoxin (TRX)] by quantitative RT-PCR in fibroblasts extracted from skin biopsies from SSc patients and healthy controls.