CHI3L1 and melanoma: The extracellular interaction between IL-13Rα2 and Chi3L1 regulates pathogen responses, oxidant injury, inflammation, and melanoma metastasis [39], and also Chi3L1 activates the Wnt/β-catenin, mitogen-activated protein kinase (MAPK), and Protein kinase B (PKB/AKT) signaling pathways via IL-13Rα2 [39] In addition, transmembrane protein 219 (TMEM219), a membrane protein plays a critical role in Chi3L1-induced IL-13Rα2 mediated signaling and responses including oxidant-induced apoptosis, lung injury, and melanoma metastasis [40].