Interestingly, IL-1β stimulation in all tested brain cell lines (A172; glioblastoma, IMR-32; neuroblastoma, and T98G; glioblastoma) severely reduced IFN-γ-induced IDO1 mRNA expression levels in a manner similar to or greater than that of the liver cell lines (Figure 1B). Here, IFNG is linked to glioblastoma.