Marcia Gay Harden is to play Christian Grey's mom in the Fifty Shades of Grey movie. The actress will star as Dr. Grace Trevelyan Grey, who adopts Christian (Jamie Dornan) when his birth mother dies. Harden, who stars on HBO's The Newsroom and ABC's Trophy Wife, played opposite Tim Robbins in the Academy Award winning movie “Mystic River”.

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Meanwhile, British singer Rita Ora has been cast as Christian Grey's adopted sister, Mia, in the big screen adaptation of the steamy bestseller by E.L. James, reports Variety. Ora joins stars Jamie Dornan and Dakota Johnson, who play lovers Christian Grey and Anastasia Steele.

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Dornan - who replaced Charlie Hunnam as Christian Grey - recently said that he is not "afraid" of taking on the role. Meanwhile, author EL James has said that she is "terrified" of her book being adapted into a highly-anticipated film.

Fifty Shades of Grey will be released on Valentine's Day weekend in 2015.