Nicotinamide phosphoribosyltransferase,NAmPRTase,Nampt,Pre-B-cell colony-enhancing factor 1 (Pre-B cell-enhancing factor),Visfatin,NAMPT,PBEF,PBEF1,PBEF (pre-B cell colony-enhancing factor), also known as visfatin and nicotinamide phosphoribosyltransferase, is an approximately 52 kDa member of the NAPRTase family of molecules. It functions both intracellularly and extracellularly, where it participates in NAD synthesis and insulin receptor activation, respectively.