As previously reported, Oscar winner Chris Cooper is also in negotiations to join the Weinstein Company film, which will be produced by a team that includes Academy Award winner George Clooney and Grant Heslov.

The only confirmed cast members for the juicy family drama of sex, drugs, lies and secrets are Julia Roberts ("Erin Brockovich") as take-no-prisoners daughter Barbara and Meryl Streep ("The Iron Lady") as her mother, Violet, the cancer-sick drug addict whose husband goes missing. Both actresses are Oscar winners.

Cooper, who was seen on Broadway in Of the Fields, Lately and is an Oscar winner for his work in "Adaptation," is in talks to play Charlie Aiken, Violet's brother-in-law. Lewis, an Oscar nominee for her performance in "Cape Fear," would play Karen, the youngest daughter of the Weston family.

The darkly comic drama, which also won the Tony Award as Best Play, is a large ensemble piece (with three sisters at its core) set in a rambling house in Oklahoma. Letts also penned the screenplay.

Clooney is an Academy Award-winning actor ("Syriana") and an Academy Award-nominated filmmaker ("Good Night and Good Luck," "The Idea of March"). Heslov is an Academy Award-nominated producer/screenwriter ("Good Night and Good Luck," "The Ides of March"). John Wells (TV's "E.R." and "Shameless") will direct. Additional casting will be announced.

Clooney and Heslov join Jean Doumanian Productions and Steve Traxler as producers. Claire Rudnick Polstein is the executive producer. 

Clooney said in a statement, "Grant and I are thrilled to work on this project. It's already a great cast and great material and I can't think of anyone better than Harvey to put this all together. And we're particularly excited to work with our dear friend John Wells. It’s such a terrific group and we feel honored to help bring it to the screen."

Here's how TWC characterizes the picture: It "tells the dark, hilarious and deeply touching story of the strong-willed women of the Weston family, whose lives have diverged until a family crisis brings them back to the Midwest house they grew up in, and to the dysfunctional woman who raised them. Letts' play made its Broadway debut in December 2007 after premiering at Chicago's legendary Steppenwolf Theatre earlier that year. It continued with a successful international run."