NEW YORK – NBC Universal is confirming that Lauren Graham has joined the cast of NBC's upcoming series "Parenthood."

Graham, best known from the longrunning "Gilmore Girls," steps into the "Parenthood" ensemble as a replacement for Maura Tierney (MOHR'-uh TEER'-nee). Tierney was forced to drop out of the series this summer after being diagnosed with breast cancer, for which she continues to get treatment.

Originally slotted for a fall premiere, "Parenthood" is now set to debut in early 2010. NBC said Monday that production begins in mid-November.

Also starring Craig T. Nelson, Bonnie Bedelia and Mae Whitman, the series is based on the 1989 movie that starred Steve Martin.