NNT and hepatocellular carcinoma: The overexpression of nicotinamide nucleotide transhydrogenase (NNT), a mitochondrial enzyme involved in the generation of NADPH from NADH and found to enhance anti-oxidant capacity, induces differentiation and reduces clonogenicity of glioblastoma tumor-initiating cells [191], whereas a reduction in NAD+ facilitates metastasis of hepatocellular carcinoma cells [192].