Moreover, using ALDH1A1 mutants that retained this GSH/DHLA-dependent NAD+-reduction activity but lost the aldehyde dehydrogenase activity, we found that ALDH1A1 can decrease the cellular NAD+/NADH ratio and promote tumor growth in xenograft models via the GSH/DHLA-dependent NAD+-reduction activity. Here, ALDH1A1 is linked to neoplasm.