IDH1 and cancer: Recent studies suggest a variety of mitochondrial and cytosolic isozymes promoting cancer-specific proliferation, highlighting a growing need for methodologies for probing subcellular level metabolic activities: Oncogenic mutations in either NADP-dependent cytosolic and mitochondrial isocitrate dehydrogenases (IDH1 and IDH2, respectively) in tumors result in distinct metabolic reprogramming54,55.