NAMPT and nonpapillary renal cell carcinoma: In our study, restoration of DIO1 expression resulted in moderate induction of enzymes involved in key pathways that undergo metabolic reprogramming in ccRCC tumors such as transketolase (TKT), nicotinamide phosphoribosyltransferase (NAMPT), and mitochondrial isoform of isocitrate dehydrogenase (IDH2).