Systematic exploration of NAM and its metabolites MNAM, 2PY, and 4PY in cancer, related to the expression of not only NNMT, but also NAMPT (the rate-limiting enzyme in NAD+ salvage pathway) and AOX1 (oxidizes MNAM to 2-PY and 4-PY), may provide a better insight into their function. The gene discussed is NNMT; the disease is cancer.