Indeed, using the commercially available PE-conjugated B-D13 mouse monoclonal antibody (B-D13-PE; Cell Sciences) reported to target IL13Rα2, we find that cell surface antigen expression on negative or low expressing glioma cell lines (T98, PBT003-4, PBT008 and PBT017-4) is up-regulated following incubation with either TNF and IL-4, or TNF and IL-13 (Figure 1A). Here, IL13 is linked to central nervous system cancer.