Integrys Energy Group, Inc. is a holding company for regulated utility and non-regulated business units. As of December 31, 2007, Integrys Energy Group served approximately 485,000 regulated electric utility customers and approximately 1,674,000 regulated natural gas utility customers. At December 31, 2007, Integrys Energy Group reported five segments: the two regulated segments include the regulated electric utility operations of Wisconsin Public Service Corporation (WPSC) and Upper Peninsula Power Company (UPPCO), and the regulated natural gas utility operations of WPSC, Michigan Gas Utilities Corporation (MGUC), Minnesota Energy Resources Corporation (MERC), The Peoples Gas Light and Coke Company (PGL), and North Shore Gas Company (NSG).(Source: 10-K)