We show that higher expression of NNMT mRNA in glioblastoma compared to nontumor samples (37) is amplified by dexamethasone that further stimulates expression of NNMT in glioblastoma cells (Fig. 4, J and K), contributing to the differential levels of N1-methylnicotinamide between the tumor and edematous brain tissue observed in patients with glioblastoma (Fig. 4T). The gene discussed is NNMT; the disease is glioblastoma.