Entity

State of Incorporation

Bright Star Partnership

Texas

Centrahoma Processing LLC

Delaware

Jefferson Gas Gathering Company, L.L.C.

Delaware

MarkWest Blackhawk, L.L.C. 

Texas

MarkWest Bluestone Ethane Pipeline, L.L.C. 

Delaware

MarkWest Buffalo Creek Gas Company, L.L.C. 

Oklahoma

MarkWest EMG Jefferson Dry Gas Gathering Company, L.L.C.

Delaware

MarkWest Energy Appalachia, L.L.C. 

Delaware

MarkWest Energy East Texas Gas Company, L.L.C. 

Delaware

MarkWest Energy Finance Corporation

Delaware

MarkWest Energy GP, L.L.C. 

Delaware

MarkWest Energy Operating Company, L.L.C. 

Delaware

MarkWest Energy South Texas Gas Company, L.L.C. 

Delaware

MarkWest Energy West Texas Gas Company, L.L.C.

Delaware

MarkWest Gas Marketing, L.L.C.

Texas

MarkWest Gas Services, L.L.C.

Texas

MarkWest Hydrocarbon, Inc.

Delaware

MarkWest Javelina Company, L.L.C.

Texas

MarkWest Javelina Pipeline Company, L.L.C.

Texas

MarkWest Liberty Bluestone, L.L.C.

Delaware

MarkWest Liberty Ethane Pipeline, L.L.C.

Delaware

MarkWest Liberty Gas Gathering, L.L.C.

Delaware

MarkWest Liberty Midstream & Resources, L.L.C.

Delaware

MarkWest Mariner Pipeline, L.L.C.

Delaware

MarkWest Marketing, L.L.C.

Delaware

MarkWest McAlester, L.L.C.

Oklahoma

MarkWest Michigan Pipeline Company, L.L.C.

Michigan

MarkWest Mountaineer Pipeline Company, L.L.C.

Delaware

MarkWest New Mexico, L.L.C.

Texas

MarkWest Ohio Fractionation Company, L.L.C.

Delaware

MarkWest Oklahoma Gas Company, L.L.C.

Oklahoma

MarkWest Panola Pipeline, L.L.C.

Texas

MarkWest Pinnacle, L.L.C.

Texas

MarkWest Pioneer, L.L.C.

Delaware

MarkWest Pipeline Company, L.L.C.

Texas

MarkWest PNG Utility, L.L.C.

Texas

MarkWest POET, L.L.C.

Delaware

MarkWest Power Tex, L.L.C.

Texas

MarkWest Ranger Pipeline Company, L.L.C.

Delaware

MarkWest Texas LPG Pipeline, L.L.C.

Texas

MarkWest Texas PNG Utility, L.L.C.

Texas

MarkWest Utica EMG Condensate, L.L.C.

Delaware

MarkWest Utica EMG, L.L.C.

Delaware

MarkWest Utica Operating Company, L.L.C.

Delaware

Mason Pipeline Limited Liability Company

Michigan

Matrex, L.L.C.

Michigan

Mule Sidetracks, L.L.C.

Delaware

Mule Tracts, L.L.C.

Delaware

Ohio Condensate Company, L.L.C.

Delaware

Ohio Gathering Company, L.L.C.

Delaware

Ohio Utica Jefferson Dry Gas Gathering Company, L.L.C.

Delaware

Panola Pipeline Company, LLC

Texas

West Relay Gathering Company, L.L.C.

Delaware

West Shore Processing Company, L.L.C.

Michigan

Wirth Gathering, a general partnership

Oklahoma