To determine whether IL-1α and IL-1β have differential effects on GBM development and whether the IL-1β effect is tumor genotype dependent, we leveraged the RCAS/Ntv-a somatic cell type–specific gene-transfer system to create a series of genetically engineered mouse models (GEMM) representing the human PN and MES GBM molecular subtypes (15). This evidence concerns the gene IL1B and neoplasm.