IL13RA2 and neoplasm: However, recent studies demonstrated that IL-13-mediated IL-13Rα2 signaling occurs via STAT6-independent pathways, involving activation of activator protein 1 (AP-1) and extracellular signal-related kinase (ERK), promoting tumor invasion, metastasis, and production of transforming growth factor beta (TGFβ) (4–9).