Mr. Walker has served as a director of the general partner of Western Gas Partners, LP since August 2007, and he also served as Chairman of the general partner of Western Gas Partners, LP from August 2007 to September 2009. He has served as a director of the general partner of Western Gas Equity Partners, LP since September 2012. Mr. Walker is President and Chief Executive Officer of Anadarko Petroleum Corporation, having joined Anadarko in 2005 as Senior Vice President and Chief Financial Officer and later serving as President and Chief Operating Officer. Mr. Walker serves as a director of Anadarko (NYSE:APC) and CenterPoint Energy, Inc. (NYSE: CNP), and also serves on the Board of Trustees of the Houston Museum of Natural Science.