Since the in vitro anti-cancer activity observed upon combining NAMPT and NAPRT inhibitors was abrogated when NA was exogenously added in excess to the culture media, it could be argued that the in vivo activity of this combination therapy might be compromised when NA levels rise considerably in the body, as could happen in response to NA- or NAM-rich diets or to NA supplements (e.g., NA is used in gram doses in cases of dyslipidemia due to its lipid-modifying effects) [44]. This evidence concerns the gene NAPRT and cancer.