STAT3 and lung carcinoma: In this context, recent reports on the newly identified role of IL-6 in epithelial cancer, such as breast and lung carcinomas, are intriguing in that IL-6 has been implicated in tumorigenesis via the IL-6 receptor-activation-mediated phosphorylation of STAT3 [48,49] and that release of IL-6 results in a positive feedback loop causing further IL-6 upregulation and secretion.