DDAH1 and neoplasm: Metabolic reprogramming in CRC regarding L-arginine/NO pathway includes overexpression of dimethylarginine dimethylaminohydrolases (DDAH1 and DDAH2) and protein methyltransferases (PRMT1 and PRMT5), in addition to ARG1 and NOS2. Importantly, transcriptional pattern of the pathway enzymes is altered not only in tumors, but also, or even only, in non-transformed tumor-adjacent tissue, contributing to the phenomenon of tumor molecular margin.