Our previous study has shown that using FK866, an Nampt (nicotinamide phosphoribosyltransferase; a rate-limiting enzyme in the NAD+ synthetic salvage pathway from NAM to NAD+) inhibitor, to mimic vitamin B3 deficiency in human Hs68 cells can reduce the lifespan of Hs68 cells, suggesting that vitamin B3 deficiency can potentially induce aging [8]. Here, NAMPT is linked to Vitamin B3 deficiency.