The increase in TRP catabolism with concomitant increases in KYN concentrations undoubtedly translated into higher KYN/TRP ratios, as our findings showed that KP activation (KYN/TRP ratio) was significantly increased in glioma after stimulating with IFN-γ for 48 and 72 hours compared to untreated cells. This evidence concerns the gene IFNG and central nervous system cancer.