When Jerome Robbins died in late July, many of the tributes and obituaries noted that after his tremendous success in Fiddler on the Roof in 1964, he never again returned to the Broadway musical stage until in the late 1980's when he put together his anthology of dance works in Jerome Robbins' Broadway. Whenever he was asked why he abandoned theatre in favor of the dance world, he would reply very succinctly, "No collaborators."

Playwright Moss Hart, on the other hand, loved the rough and tumble of collaboration, particularly as evidenced in his classic 1948 stage comedy, Light Up the Sky, which the La Jolla Playhouse is presenting in a 50th anniversary production through Sept. 27. The show is an affectionate backstage look at the foibles and frailties of an obsessive group of show folk on the night when their new production opens in Boston on its way, hopefully, to Broadway. The types are familiar -- if from another era: the boorish producer, the emotionally extravagant, larger-than-life star, the hopeful young playwright (and the cynical old one) and the high-strung director who, as one character put it, "cries at card tricks."

Unlike behind-the-scenes spoofs of Hollywood filmmaking, which often center on greed and venality (Four Dogs and a Bone; Speed the Plow; Mizlansky/Zilinksy or "schmucks"), playwrights who look at the theatre invariably combine their jabs and the childishness and ego of the players with a real affection and romantic view of its crazy world. That was especially true of Moss Hart, who co-authored with George S. Kaufman such great classics as Once in a Lifetime, The Man Who Came to Dinner and You Can't Take It With You.

"Moss loved the theatre and simply adored actors; that's what made him such a good director," says Kitty Carlisle Hart, his widow and the keeper of the Hart flame who herself toured in many of her husband's productions, including Light Up the Sky. (She will not, however, be involved in the La Jolla production.) "I think he really found something terribly exciting about what happens when you have a group of people in a hotel room trying to solve this complicated, difficult process of putting on a play. He never tired of it. He was inspired by it."

Now that Broadway shows evolve through regional and Off-Broadway productions, the out-of-town tryout is more and more an exotic experience. And, indeed, the world evoked in Light Up the Sky may seem somewhat foreign and topical (the characters of both the producer and star were based on the legendary Billy Rose and Gertrude Lawrence, respectively). But Neel Keller, who is directing the show, says that its relevance applies to any collaborative effort -- whether it be a secretary pool, a sports team or the conference room of a law office or stock brokerage. "Hart was really interested in people's ability to be swayed," he says, "to have their beliefs and dreams strongly challenged by doubts and recriminations, so that they wonder whether they were right to believe what they believed in the first place."

Hart has a lot of fun spoofing and pricking the balloons of his delusion-prone characters in Light Up the Sky. But ultimately, says Keller, through the character of the playwright, "he addresses our real ability to stick to what we believe in and to be true to that." -- By Patrick Pacheco