Cynthia Nixon Cast on The Big C

Cynthia Nixon has agreed to her first post-Sex and the City role.

The actress, who rose to fame as Mirando on that HBO hit, will play the best friend of Laura Linney's main character, Cathy, on The Big C.

Premiering August 16 on Showtime, The Big C centers on Cathy, a repressed suburban wife/mother who takes on a new attitude after she's diagnosed with cancer. Oliver Platt, Gabourey Sidibe and Idris Elba will also play key roles.

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