A study of 66 patient glioma samples revealed that 71% of GBM tumor samples had higher than 50% COX-2 positive cells (3% had less than 25% COX-2 positive cells) compared to 30% COX-2 positive cells of low-grade gliomas (40% had less than 25% COX-2 positive cells) (72). Here, PTGS2 is linked to glioma.