CHI3L1 and glioblastoma: IL-13Rα2 is the most common therapeutic target in glioma; Recent studies have shown that IL-13Rα2 can signal through the AP-1 pathway where it cooperates with other molecules, such as chitinase 3-like 1 (CHI3L1) [36] and epidermal growth factor receptor variant III (EGFRvIII), in glioblastoma [19, 37].