Conversely, NNMT, encoding for the enzyme responsible for the synthesis of N1-methylnicotinamide (Fig. 3D), was among the 79 transcripts up-regulated by dexamethasone in all four glioblastoma cell lines (Figs. 1I and 3E), and its expression pattern was confirmed at the protein level (Fig. 3F). Here, NNMT is linked to glioblastoma.