SIRT1 and neoplasm: The results showed that tumor growth was significantly enhanced by NMN, which is consistent with the role of SIRT1 in promoting tumor progression.[53, 54] In contrast, cotreatment with EX527 inhibited tumor growth, compared to that with NMN alone, demonstrating that SIRT1 activity accelerated tumor growth and that its inhibition had the opposite effect (Figure 6B–E).