In contrast to normal cells where Stat3 activation is a transient process, Stat3 is persistently activated in a number of epithelial tumors including breast cancer and there is increasing evidence demonstrating that activated Stat3 plays a critical role in the pathogenesis of breast cancer including metastatic progression and response to therapy [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19]. The gene discussed is STAT3; the disease is breast carcinoma.