NOTCH1 and acute lymphoblastic leukemia: To investigate how the meningeal microenvironment responds to T-ALL–derived cytokines, we evaluated the expression of TNFR1, IL-27R-α, and IFNGR1 on meningeal stromal and immune cells, and confirmed elevated receptor expression on mural (fibroblasts and pericytes) meningeal cells in ΔE-NOTCH1 mice (Figure 8I).