The aims of this study were to determine the expression, and clinical importance, of total- and phospho(Thr172)- AMPKα in early-stage invasive breast cancer from patients treated with radiotherapy and to investigate the effect of metformin on the radiosensitivity of different phenotypes of breast cancer cells, assessing if changes in redox homeostasis, due to alterations in Trx system proteins, played a role in any altered radiosensitivity. The gene discussed is TXN; the disease is breast cancer.