PARP1 and neoplasm: Particularly, besides the induction of tryptophan degradation for cell growth inhibition, IFN-γ inhibited tumor cell growth more extensively by the depletion of NAD+ via activating poly (ADP-ribose) polymerase family member 1 (PARP1), which was also known as adenosine diphosphate ribosyl transferase (ADPRT) [39].