OPA1 and neoplasm: To determine whether Opa1 deletion sensitizes cells to inhibition of cytoplasmic NAD+ regeneration, we measured viability of tumor cells treated with DMSO, the lactate dehydrogenase inhibitor GNE-140,36 or the PDK inhibitor AZD7545 that activates PDH and drives pyruvate into mitochondria and away from lactate synthesis.