STAT3 and cancer: Indeed, the elevated serum levels of IL-6 or IL-6 family ligands (e.g., IL-11, Leukemia Inhibitory Factor) associated with robust activation of the STAT3 pathway in skeletal muscle has been demonstrated in different cancer models in advanced stages, such as C26 (13, 15), ApcMin mice (14), and Lewis lung adenocarcinoma (17).