To elucidate whether these pathways were active, we assessed the expression of several genes associated with the type I IFN system (IFNβ, MX1, and ISG15) and the NF-κB pathway (IκBα, IL1β, and TNFα) in irradiated senescence-enriched GBM cell populations and non-irradiated controls 7 days following radiation treatments. The gene discussed is ISG15; the disease is glioblastoma.