Question: When was the American drama television series which Peter Horton played ole of Professor Gary Shepherd on aired 

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Dirty Sexy Money: Dirty Sexy Money is an American prime time drama series created by Craig Wright.  It ran on ABC from September 26, 2007 to August 8, 2009.  The series was produced by ABC Studios, Bad Hat Harry Productions, Berlanti Television and Gross Entertainment.  Wright served as an executive producer alongside Greg Berlanti, Bryan Singer, Matthew Gross, Peter Horton, and Josh Reims, with Melissa Berman producing.

The Cure (1995 film): The Cure is a 1995 American drama film starring Brad Renfro and Joseph Mazzello.  The film follows two boys searching for the cure of AIDS, from which one of them is suffering.  It was directed by Peter Horton and written by Robert Kuhn.

Mark Sloan (Grey's Anatomy): Mark Everett Sloan, M.D., F.A.C.S. is a fictional surgeon from the ABC medical drama television series "Grey's Anatomy", portrayed by Eric Dane.  Dr. Sloan is an attending specializing in plastic surgery.  Dr. Sloan earned the nickname “McSteamy” for his good looks by the female interns of Seattle Grace later Seattle Grace Mercy West Hospital.  He was good friends with Dr. Derek Shepherd, a fellow physician at Seattle Grace, but was the catalyst for the end of Shepherd's marriage when Shepherd caught Sloan sleeping with his wife, Addison.  Later, he pursues a 'forbidden' relationship with Dr. Lexie Grey, straining his relationship with Derek yet again.  He reveals that he loves Lexie in episodes "Migration", "Flight", "Going, Going, Gone", and "Remember The Time" In the show's ninth season, he dies of injuries sustained in a jet plane crash that also injured or killed several of his colleagues from the hospital.

American Odyssey: American Odyssey (known in the UK under its original title Odyssey) is an American thriller television series which premiered on April 5, 2015, on NBC.  Created by Peter Horton, Adam Armus and Kay Foster, the series revolves around the discovery by a U.S. Army team on a secret mission in Mali, that a major U.S. company has been funding Islamist terror groups, and the subsequent cover-up of this revelation, which involves the attack and killing of the team of U.S. soldiers by private military contractors dispatched by the same company.

Thirtysomething: Thirtysomething (stylized as thirtysomething) is an American drama television series created by Ed Zwick and Marshall Herskovitz for ABC that aired from 1987 to 1991.  It tells of baby boomers living in their thirties who reside in Philadelphia, Pennsylvania, and examines how this group of friends learn to negotiate their prior involvement with the early 1970s counterculture as young adults, in contrast to the yuppie lifestyle which .

As We Know It: "As We Know It" is the seventeenth episode of the second season of the American television medical drama "Grey's Anatomy".  The episode was written by Shonda Rhimes and was directed by Peter Horton.  It originally aired on the American Broadcasting Company (ABC), on February 12, 2006, running for 43:06 min.  This episode is the second of a two-part story.

Peter Horton: Peter Horton (born August 20, 1953) is an American actor and director.  He is perhaps best known for the role of Professor Gary Shepherd on the television series "Thirtysomething" which he played from 1987 until 1991.

The Philanthropist (TV series): The Philanthropist was an American action drama series that premiered on NBC on Wednesday, June 24, 2009.  The program was a limited summer series, principally filmed in South Africa.  It opened to strong ratings, but saw a drop in viewers in subsequent weeks.  "The Philanthropist" is a Carnival Films production in association with The Levinson/Fontana Company and Original Media.  Tom Fontana, Barry Levinson, Peter Horton, Charlie Corwin, Gareth Neame, and Teri Weinberg served as executive producers.

Life Unexpected: Life Unexpected is an American drama television series that aired for two seasons from 2010 to 2011.  It was produced by Best Day Ever Productions and Mojo Films in association with CBS Productions and Warner Bros.  Television and broadcast by The CW.  Created by Liz Tigelaar, who served as an executive producer with Gary Fleder and Janet Leahy, the series stars Britt Robertson, Shiri Appleby, Kristoffer Polaha, and Kerr Smith.

Pilot (Dirty Sexy Money): "Pilot" is the first episode of the ABC television series, "Dirty Sexy Money".  The episode was written by Craig Wright and was directed by Peter Horton.  It originally aired on Wednesday, September 26, 2007.

Supporting paragraphs: Peter Horton Thirtysomething
Answer: from 1987 to 1991