NAMPT and neoplasm: The mechanism by which NAMPT is fundamental in tumor progression certainly relies on the fact that NAD+ is required for the activity of NAD+-metabolizing enzymes, such as PARP1, SIRT1, SIRT6 and CD38, all having different cancer-promoting abilities, such as genomic stability, secretion of pro-inflammatory cytokines, angiogenesis, motility and invasion [8–11].