In other contexts, mitochondrial pyrroline 5-carboxylate reductase 1 (PYCR1) redirects excess mitochondrial NADH and/or glutamate towards proline synthesis in isocitrate dehydrogenase 1 (IDH1) mutant glioma cells, leading to a partially uncoupled TCA cycle that allows cells to regulate mitochondrial NAD+/NADH [22]. This evidence concerns the gene PYCR1 and central nervous system cancer.