IL13RA2 and central nervous system cancer: Toxins have been evaluated in several anti-glioma studies targeting IL13Rα2, the urokinase-type plasminogen activator (uPA) receptor, growth factor receptors and transferrin receptors, due to their differential expression status in glioma cells when compared to normal brain cells (Candolfi et al., 2011; Castro et al., 2011).