Credit: Michael N. Todaro/FilmMagic

Lauren Graham has joined the cast of NBC's upcoming series Parenthood.

The network confirms that the former Gilmore Girls star, 42, will be replacing Maura Tierney, who was forced to drop out of the series in order to undergo treatment for breast cancer.

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In July, the former ER star, 44, revealed that she found a tumor in her breast that required surgery. At the time, she was not certain of her exact diagnosis or course of treatment, but in September, her spokesperson said in a statement that it conflicted with the series' filming schedule.

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Production on Parenthood -- a contemporary reimagining of the 1989 comedy -- will begin in mid-November, NBC confirms to the Associated Press.

The show, which was originally slated to premiere this fall, is now set to debut early next year.

Parenthood will be Graham's first role as a series regular since Gilmore Girls ended in 2007. Most recently, Graham made her Broadway debut in February as Miss Adelaide in the revival of Guys and Dolls in NYC.