Laura Dern has joined the cast of Robert Altman’s “Dr. T and the Women,” playing a young mother of three who’s dumped by her husband. She joins Richard Gere, Helen Hunt, Goldie Hawn and Kate Hudson. Dern will next be seen in another ensembler, “Daddy and Them,” written and directed by Billy Bob Thornton for Miramax.

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Josh Lucas will join Sean Penn and Catherine McCormack in Kathryn Bigelow’s “The Weight of Water.”

Lucas will also appear opposite Christian Bale in Mary Harron’s upcoming “American Psycho,” in Fox Searchlight’s “The Dancer” for helmer Luc Besson and alongside Laura Linney in the indie “You Can Count on Me.” He is repped by ICM.

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After appearing in this summer’s high school hit “American Pie,” Seann William Scott has landed a role in the DreamWorks comedy “Road Trip,” exec produced by Ivan Reitman. Docu helmer Todd Phillips (“Frat House”) is directing; Dan Goldberg and Joe Medjusk serve as producers.

“Road Trip” follows college students on a jaunt from one campus to another in order to intercept a compromising video.

Scott recently completed lensing on New Line’s “Flight 180.” He is repped by Chuck James and Lorrie Bartlett of the Gersh Agency and manager Warren Zide.

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David Newsom has been added to the cast of the ABC/Disney series “Talk to Me” alongside star Kyra Sedgwick. Newsom will play her best friend and sidekick in the sitcom about a single, successful radio talkshow host living in New York. Newsom previously had a development deal at NBC and starred in the short-lived “House Rules” and the ABC drama “Homefront.” He is repped by Innovative Artists.

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Nestor Serrano has been added to the cast of the Castle Rock comedy “Bait,” starring Jamie Foxx.

Serrano will next appear in Martin Scorsese’s “Bringing Out the Dead,” starring Nicolas Cage, and Touchstone’s “The Insider” with Al Pacino, Russell Crowe and Gina Gershon. He is repped by Dina Barone & Co.

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Steven Culp (CBS’ “Jag”) and Tim Kelleher (“The Negotiator”) have joined the Beacon/Universal pic “Thirteen Days,” starring Kevin Costner.

Culp, who has extensive TV credits, will next appear in Neil LaBute’s “Nurse Betty,” starring Renee Zellweger. He is repped by Suzanne Bennett of the Paul Kohner Agency and manager Miriam Milgrom.

He is repped by manager Jamie M. Gold of Incognito Management.