This study investigates the roles of nicotinamide riboside kinases (NRKs), specifically NRK1 and NRK2, in the metabolism of nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) within skeletal muscle cells. Utilizing genetic knockout models and metabolic flux analyses, the researchers demonstrate that NRK1 and NRK2 exhibit functional redundancy in phosphorylating NR
