Similarly, Prx-I over-expression is associated with diminished overall survival, poor clinical outcome, and resistance of cancer cells to radiotherapy and chemotherapy [26]–[28], while the down-expression of Prx-I by RNAi is associated with therapeutic challenges for liver cancer, esophageal cancer, and thyroid cancer [29]–[31]. The gene discussed is PRDX1; the disease is thyroid cancer.