As we recently showed, expression of COX4-1 is associated with enhanced ability to repair radiation-induced DNA damage in glioma cells [4,5], suggesting that the high rates of de novo purine synthesis in COX4-1-overexpressing glioma cells may contribute to the more aggressive and radioresistant phenotype observed upon the switch from COX4-2 to COX4-1 expression. Here, COX4I2 is linked to central nervous system cancer.