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STEVEN BARKER

Subjects: All Subjects

Links:Website

Member of the Oklahoma Bar Association

Published multiple works in The Oklahoman

Steven Barker joined Cornerstone as a Principal in our Oklahoma office in November 2025.

Prior to Cornerstone he served as Assistant Municipal Counselor for the City of Oklahoma City. In this role, he represented the city in eminent domain and land use matters, advised the City Manager's Office and Planning Department and supported key strategic initiatives, including securing a 25-year lease agreement with the Oklahoma City Thunder.

Previously, Steven served as General Counsel at Coop Ale Works, providing nationwide regulatory guidance to support product distribution. In this role, he managed all federal and state compliance, negotiated agreements with distributors and oversaw the company's licensing portfolio.

Earlier in his career, Steven worked with the Oklahoma Alcoholic Beverage Laws Enforcement Commission, where he held leadership roles as Deputy Director and General Counsel. He has also served as an Assistant Attorney General in the Oklahoma Attorney General's Office and as Assistant General Counsel with the Oklahoma Tax Commission. Steven currently serves as Chief Municipal Judge for the City of Warr Acres, where he presides over arraignment, juvenile and trial dockets.

Steven holds a Juris Doctor from Oklahoma City University School of Law and a Bachelor of Arts in Political Science from Pittsburg State University.

LAUREN MCCAY

Subjects: All Subjects

Links:Website

Assists the firm's Oklahoma City government relations team with client service activities including conducting research and providing updates on state legislative matters and diverse regulatory issues

Previously served as account executive at Lilly & Company

Former congressional intern for Representative Stephanie Bice (R-OK)

Lauren McCay serves as a Senior Associate in Cornerstone's Oklahoma City office, assisting the firm's government relations team with client service activities including conducting research and providing updates on state legislative matters and diverse regulatory issues.

Lauren comes to Cornerstone from Lilly & Company where she led the firm's highly successful fundraising effort in Oklahoma as an Account Executive. She was responsible for executing numerous fundraisers and meeting fundraising goals for current federal legislators and those seeking office in the U.S House and Senate.

Before joining Lilly & Company, Lauren served as a Congressional Intern for Representative Stephanie Bice (R-OK) where she managed and answered constituent inquiries while also supporting staff by taking initiative on various district office projects and case work.

Lauren received her Bachelor of Science in political science from the University of Oklahoma.

JON YATES

  • (405) 938-7138

  • 141 NE 13TH STREET SUITE 200OKLAHOMA CITYOK73104

Subjects: All Subjects

Links:Website

Respected public policy professional with experience in statewide campaigns, legislative engagement, and building strategic partnerships

Former vice president at Advanced Power Alliance

Former vice president of field operations at the Oklahoma Farm Bureau

Mark Yates joined Cornerstone in July 2021 as a principal in the firm's Oklahoma City office. His experience in public policy includes working with various industries through statewide campaigns, legislative engagement, media relations, and public speaking. Mark has been successful navigating complex and challenging initiatives on behalf of the clean energy and agriculture industries.

Mark previously served as vice president at Advanced Power Alliance (APA) where he represented leading domestic and international companies in the renewable energy sector. While in this role, he managed the association's regional public policy strategy, communications strategy, and membership recruitment efforts. Mark served a major role in shaping legislative and regulatory policy within the most important energy region in the country.

Prior to APA, Mark worked at the Oklahoma Farm Bureau, where he led membership recruitment initiatives, mobilized a statewide grassroots campaign, and lobbied for rural issues on behalf of the nearly 90,000 farmers and ranchers.

Before his time with the Farm Bureau, Mark was a professional educator in the Oklahoma public school system for 11 years. Along with his teaching experience, Mark also had administrative experience serving as a federal programs director for Plainview Public Schools in Ardmore, OK.

Mark is a graduate of East Central University in Ada, OK and holds a bachelor's degree in History and master's in Secondary Administration. Mark and his wife Stacy reside in Edmond, OK where they are active in their community and have two children, Londyn and Steele.

Clients:

NEIL ALLDREDGE

(Indiana)

NEIL ALLDREDGE

(Indiana)
  • (317) 876-4205

  • 10 W 106th StreetSuite 100IndianapolisIN46290

PHILLIP ARNZEN

(Nebraska)
  • 10 W 10th Street, Suite 100IndianapolisIN46290

PHILLIP ARNZEN

(Colorado)
  • 317-876-4205

  • 10 W 106th Street, Suite 100IndianapolisIN46290 

PHILLIP ARNZEN

(North Dakota)
  • (317) 876-4205

  • 10 W 106TH STSTE 100CARMELIN46290-1002

PHILLIP ARNZEN

(Iowa)
  • 317-876-4205

  • 10 W. 106th Street, Suite 100IndianapolisIN46290

Clients:
Clients:

BRIAN CHRISTENBERRY

BRIAN CHRISTENBERRY

(Indiana)

BRIAN CHRISTENBERRY

BRIAN CHRISTENBERRY

(Indiana)

BRIAN CHRISTENBERRY

BRIAN CHRISTENBERRY

(Michigan)
  • (703) 684-1110

  • 1000 WILSON BLVDSTE 1800 % MULTISTATE ASSOCIATES LLCARLINGTONVA22209

BRIAN CHRISTENBERRY

BRIAN CHRISTENBERRY

(Wisconsin)

BRIAN CHRISTENBERRY

BRIAN CHRISTENBERRY

(Illinois)
  • 20 F Street NWSuite 510WashingtonDC20001

Clients:
  • 202-559-0170

  • 800 North Capitol Street, NW, Suite 800WashingtonDC20002

Clients:

1) 3M COMPANY

2) ACCRETE AI GOVERNMENT, LLC

3) ADVANCED MEDICAL TECHNOLOGY ASSOCIATION (ADVAMED)

4) AEROSTAR INTERNATIONAL, LLC

5) AICPA ASSOCIATION OF INTERNATIONAL CERTIFIED PROFESSIONAL ACCOUNTANTS

6) AIRLINES FOR AMERICA

7) ALABAMA-COUSHATTA TRIBE OF TEXAS

8) ALKERMES, INC.

9) ALLY FINANCIAL INC.

10) ALTRIA CLIENT SERVICES LLC

11) ALTUMINT, INC.

12) AMERICAN ASSOCIATION OF COLLEGES OF OSTEOPATHIC MEDICINE

13) ANNE PRAMAGGIORE

14) ARRAY TECHNOLOGIES, INC.

15) ASSOCIATION FOR MATERIALS PROTECTION AND PERFORMANCE (AMPP)

16) ASSOCIATION OF PRIVATE NON-PROFIT INSTITUTIONS

17) AT&T SERVICES, INC.

18) ATKINSREALIS NUCLEAR SECURED, LLC

19) AVENTIV TECHNOLOGIES LLC AND VARIOUS SUBSIDIARIES

20) BLINK HEALTH, INC.

21) BLOCK INC.

22) BROAD INSTITUTE

23) CAPITAL ONE FINANCIAL CORPORATION

24) CARLOS ARGENAL

25) CENTERSTONE

26) CGI FEDERAL INC.

27) CHESAPEAKE BAY COMMISSION

28) CHUBB INA HOLDING COMPANY INC

29) COCA-COLA BOTTLING COMPANY UNITED, INC.

30) COHERE US, INC.

31) COREWEAVE, INC.

32) CORNELL ABRAXAS GROUP, LLC

33) CORTEVA AGRISCIENCE LLC

34) COUPANG, INC.

35) DATA CENTER COALITION

36) DEFENSE CREDIT UNION COUNCIL

37) DEVON ENERGY CORPORATION

38) EDF POWER SOLUTIONS DEVELOPMENT, INC.

39) EINRIDE

40) EISAI, INC.

41) ELECTRONIC PAYMENTS COALITION

42) EVER-GREEN ENERGY, INC.

43) EXXON MOBIL CORPORATION

44) FINANCIAL SERVICES FORUM

45) FITCH RATINGS

46) GENERAL ATOMICS

47) GINKGO BIOWORKS, INC.

48) GOEL INVESTMENTS, LLC

49) GOULD INDUSTRIES LTD.

50) GREEN BUSINESS CERTIFICATION INC.

51) H&R BLOCK MANAGEMENT, LLC

52) HALEON US HOLDINGS LLC

53) HEMP BEVERAGE ALLIANCE

54) HF SINCLAIR CORPORATION

55) IDEMIA IDENTITY & SECURITY USA, LLC

56) INFIN A FINANCIAL SERVICES ALLIANCE

57) JOSHCO GROUP, LLC

58) KANE KESSLER, P.C. OBO CLARUS CORPORATION

59) KIDNEY CARE PARTNERS

60) KLASKO IMMIGRATION LAW PARTNERS, LLP ON BEHALF OF INTEALTH

61) KOCH GOVERNMENT AFFAIRS, LLC

62) KOCHAVIM BEHAVIORAL HEALTH INC.

63) LATHAM & WATKINS LLP OBO PEDIATRIC ASSOCIATES

64) LIBERTY MUTUAL GROUP INC.

65) LIFESCIENCE LOGISTICS

66) LPL FINANCIAL LLC

67) MADRIGAL PHARMACEUTICALS, INC.

68) MARSH MCLENNAN

69) MERCK & CO., INC.

70) MGM TRANSFORMERS, A FORGENT COMPANY

71) MINERALS TECHNOLOGIES INC.

72) MORGAN STANLEY & CO LLC

73) MOTOROLA SOLUTIONS, INC.

74) NATIONAL ASSOCIATION OF MUTUAL INSURANCE COMPANIES

75) NATIONAL ASSOCIATION OF REALTORS

76) NATIONAL ATHLETIC TRAINERS' ASSOCIATION

77) NATIONAL HARDWOOD LUMBER ASSOCIATION

78) NATIONAL MEDAL OF HONOR MUSEUM

79) NAVIGATE AFFORDABLE HOUSING PARTNERS, INC.

80) NIQUAN ENERGY, LLC

81) NISSAN NORTH AMERICA, INC.

82) NORFOLK SOUTHERN CORPORATION

83) NUCLEAR INNOVATION ALLIANCE

84) OCEAN AERO, INC.

85) PHARMACEUTICAL RESEARCH AND MANUFACTURERS OF AMERICA

86) PHILLIPS 66 COMPANY

87) PRECISION MOTION HEALTH

88) PROFESSIONAL GOLFERS' ASSOCIATION OF AMERICA

89) PROTON THERAPY CONSORTIUM

90) REBELLION DEFENSE, INC.

91) REFLECTION WINDOW + WALL, LLC

92) RESEARCH!AMERICA

93) ROSHEL INC.

94) ROUGH COUNTRY, LLC

95) SABLE OFFSHORE CORP.

96) SAFARI CLUB INTERNATIONAL

97) SALESFORCE.COM, INC.

98) SANOFI US SERVICES INC.

99) SECURITIES INDUSTRY AND FINANCIAL MARKETS ASSOCIATION (SIFMA)

100) SEMPRA ENERGY

101) SEYMOUR SUPPORT COUNCIL, INC. DBA FRIENDS OF SEYMOUR

102) SHIELD AI, INC.

103) SOFTWARE & INFORMATION INDUSTRY ASSOCIATION (SIIA)

104) SPRAY FOAM COALITION

105) SSA MARINE

106) STRATA CLEAN ENERGY, LLC

107) TAKEDA PHARMACEUTICALS AMERICA, INC.

108) TECHNET

109) THE BOEING COMPANY

110) THE PNC FINANCIAL SERVICES GROUP

111) THE SCORE ASSOCIATION

112) TIKTOK INC.

113) TIKTOK USDS JOINT VENTURE LLC

114) TRANSAMERICA COMPANIES

115) TRUCKERS INTEGRAL TO OUR ECONOMY INC (TIE)

116) U.S. SUGAR CORPORATION

117) UNITED STATES STEEL CORPORATION

118) UNIVERSITY OF PHOENIX

119) VERTEX PHARMACEUTICALS INCORPORATED

120) VISA, INC.

121) VMWARE, INC. OBO BROADCOM INC.

122) WORLD SHIPPING COUNCIL

123) X ENERGY, LLC

124) ZSCALER INC.

  • 20 F Street NWSuite 510WashingtonDC20001

SEAN MCLAUGHLIN

(Connecticut)

SEAN MCLAUGHLIN

(New York)
  • 3601 VINCENNES ROADINDIANAPOLISIN46268

SEAN MCLAUGHLIN

(Vermont)

SEAN MCLAUGHLIN

(Massachusetts)
  • 973-879-4602

  • 10 W 106th Street, Suite 100,Suite 100IndianapolisIN46290

SEAN MCLAUGHLIN

(Rhode Island)

SEAN MCLAUGHLIN

(Maine)

SEAN MCLAUGHLIN

(New Hampshire)

GEORGE MCNAB

(Maryland)
  • 317-875-5250

  • 3601 Vincennes RoadIndianapolisIN46268

GEORGE MCNAB

(Pennsylvania)

GEORGE MCNAB

(Ohio)
  • 6146443463

  • 10 W 106th StreetSuite 100IndianapolisIN46290

GEORGE MCNAB

(New Jersey)
  • 10 W 106th Street Suite 100IndianapolisIN46290

  • 800 North Capitol Street, NW, Suite 800WashingtonDC20002

Clients:
Clients:

1) A16Z CAPITAL MANAGEMENT, LLC

2) AFFORDABLE ASSISTED LIVING COALITION

3) AMEREN ILLINOIS

4) AMERICAN ASSOCIATION OF ORTHODONTIST

5) AMERICAN COUNCIL OF LIFE INSURERS

6) ANAPLAN INC.

7) AUTO AND TRUCK RECYCLERS OF ILLINOIS

8) BAYER U.S. LLC

9) CAPSTONE CONSULTING

10) COLLINSVILLE CUSD #10

11) COPACK INDUSTRIES LLC

12) DECATUR DOWNS LLC

13) DESTINATION ILLINOIS LLC

14) DIRECTV, LLC

15) DUCKS UNLIMITED

16) ECHOSTAR CORPORATION AND ITS AFFILIATES

17) ENTERPRISE LEASING COMPANY OF CHICAGO, LLC DBA ENTERPRISE MOBILITY

18) EXXON MOBIL CORPORATION

19) FIREMEN'S ANNUITY & BENEFIT FUND OF CHICAGO

20) FMR, LLC

21) FORESIGHT ENERGY, LLC

22) GERONIMO POWER, LLC

23) GOOGLE LLC AND ITS AFFILIATES

24) GRAND PRAIRIE WATER COMMISSION

25) HEALTH CARE COUNCIL OF ILLINOIS

26) I3 BROADBAND

27) ILLINOIS ASSOCIATION OF VOCATIONAL AGRICULTURE TEACHERS

28) ILLINOIS CENTRAL RAILROAD COMPANY

29) ILLINOIS COMMUNITY COLLEGE TRUSTEES ASSOCIATION

30) ILLINOIS HEALTH & HOSPITAL ASSOCIATION

31) ILLINOIS LIFE & HEALTH INSURANCE COUNCIL

32) ILLINOIS PHYSICAL THERAPY ASSOCIATION

33) ILLINOIS PIPE TRADES, P.E.C.

34) ILLINOIS PUBLIC HIGHER EDUCATION COOPERATIVE

35) ILLINOIS RADIOLOGICAL SOCIETY

36) ILLINOIS RETAIL MERCHANTS ASSOCIATION

37) ILLINOIS SOCIETY OF ANESTHESIOLOGISTS

38) ILLUMINATIVE STRATEGIES INC.

39) INTERNATIONAL UNION OF OPERATING ENGINEERS LOCAL 318

40) INTERNATIONAL UNION OF OPERATING ENGINEERS LOCAL 520

41) INTERNATIONAL UNION OF OPERATING ENGINEERS LOCAL 649

42) INTERNATIONAL UNION OF OPERATING ENGINEERS LOCAL 841

43) INTERNATIONAL UNION OF OPERATING ENGINEERS LOCAL 965

CHRISTOPHER NICOLOPOULOS

CHRISTOPHER NICOLOPOULOS

(Connecticut)

MATT OVERTURF

(Ohio)
  • 937.935.0432

  • 530 Eagle Walk RoadDelawareOH43015

Clients:

CHRISTIAN RATAJ

(Nevada)

CHRISTIAN RATAJ

(Alaska)

CHRISTIAN RATAJ

(Hawaii)

GINA ROTUNNO

(North Carolina)
  • (317) 875-5250

  • 10 W 106th Street, Suite 100IndianapolisIN46290

GINA ROTUNNO

(West Virginia)

GINA ROTUNNO

(South Carolina)
  • 3178764256

  • 10 W 106th Street, Suite 100IndianapolisIN46290

  • 317-876-4256

  • 3601 Vincennes RoadIndianapolisIN46268

GINA ROTUNNO

(Virginia)

GINA ROTUNNO

(Delaware)
  • 10 W. 106th Street Suite 100IndianapolisIN46290

Clients:

BRUCE SPENCER

(Montana)

CHELSEA STALLINGS

(Kansas)

CHELSEA STALLINGS

(Arizona)
  • 317-876-6227

CHELSEA STALLINGS

(Arkansas)

CHELSEA STALLINGS

(Oklahoma)
  • (317) 876-6227

  • 10 W. 106TH STREET SUITE 100INDIANAPOLISIN46290

CHELSEA STALLINGS

(Texas)
  • (317)8766227

  • 10 W. 106th StreetSuite 100IndianapolisIN46290

CHELSEA STALLINGS

(Utah)
  • (317) 876-6227

  • 10 W 106th StreetSuite 100IndianapolisIN46290

JOSHUA STEPHENS

(Mississippi)

BRANDON VICK

(Montana)

BRANDON VICK

(Washington)

BRANDON VICK

(Oregon)

BRANDON VICK

(Wyoming)

BRANDON VICK

(Idaho)
  • 10 W. 106 Street, Suite 100IndianapolisIN46290

STEPHEN VOLJAVEC

(Federal)
Clients:

ERICA WEYHENMEYER

(Illinois)