NNMT and cancer: This past year has already brought the groundbreaking discovery through MS proteomics that nicotinamide N-methyltransferase (NNMT) is the master metabolic regulator of cancer-associated fibroblasts (CAFs) 89, which are the dominant cellular component in the TME and perform metabolic and immune reprogramming of the TME, as well as alter the ECM structure through the release of various factors 90, 91.