This is again reflected in immunohistochemistry of glioma xenograft tumors (Figure 2B); high levels of CHOP and ATF4 (driven by the PERK arm of the UPR) are evident compared to normal brain, as are those of XBP-1 (where we cannot distinguish between spliced and unspliced versions with this antibody). This evidence concerns the gene ATF4 and central nervous system cancer.