NNMT and cancer: NNMT is an intracellular methyltransferase that catalyzes the N‐methylation of nicotinamide (NAM, the precursor of NAD+) to generate 1‐methylnicotinamide (1‐MNA) using SAM as the methyl donor.[17, 24] Given its function in consuming NAD+ precursor and SAM, NNMT is emerging as a crucial regulator in cellular redox and energy metabolism, as well as epigenetic regulation.[17, 25] Accumulating evidence has indicated the overexpression of NNMT with an oncogenic role in various cancer types.