CDK9 and glioblastoma: Remarkably, targeting the YY1-CDK9 complex triggered interferon (IFN) responses in GSCs, and combined CDK9/PD-1 targeting reduced immunosuppressive Treg cells and MDSCs, while increasing cytotoxic CD8+ T cells, indicating that targeting transcriptional elongation processes might rewire the GBM microenvironment, thereby enhancing ICB therapeutic strategies, in particular in the GSC population [195].