HBO said Friday that Ryan Murphy, maker of "Eat Pray Love" and the TV show "Glee," will direct the film.
Larry Kramer's play about the men who joined him to help form the Gay Men's Health Crisis debuted in 1985 and was brought to Broadway again in 2011, winning a Tony Award for best revival.
Roberts will portray Dr. Emma Brookner, a paraplegic doctor who treated several of the earliest AIDS victims. Ruffalo plays Ned Weeks, who sought answers when he saw the disease begin to kill many gay people he knew.
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