**Acknowledgements**

Most of the work of the Planas laboratory described here has been supported by grants AGL2002-03987, AGL2005-01230, CSD2007-0002 and AGL2009-07006 to JVP from the Spanish Ministry of Science and Education. The authors would like to particularly thank Dr. Amira Klip (Hospital for Sick Children, University of Toronto) and Dr. Jeffrey Pessin (Albert Einstein College of Medicine, New York) for their stimulating collaborations and interest in the comparative aspects of GLUT4 biology.
