Division of Cancer Research, School of Medicine, University of Dundee, Dundee, UK. Division of Metabolism, Endocrinology & Diabetes (MEND), Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA; Biointerfaces Institute, University of Michigan, Ann Arbor, MI, USA. Division of Molecular and Clinical Medicine, School of Medicine, University of Dundee, Dundee, UK. Electronic address: l.kang@dundee.ac.uk.