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The sisters were on the offensive, and perhaps with good reason. In a town where even modestly budgeted women's films are deemed risky business, their light, literate and relatively little film, "The Sisterhood of the Traveling Pants (search)," is widely considered The Big Chick Flick of the summer movie season.

At "Sisterhood's" tastefully understated premiere Tuesday night, star Amber Tamblyn (TV's "Joan of Arcadia (search)") addressed the "chick flick" label without it ever being mentioned to her.

"When I read (the script), it went beyond gender," she told AP Television News. "It transcended gender, which means that the story points are about sexuality and culture diversity and friendship and death and things that anybody can relate to."

Tamblyn's co-stars — Alexis Bledel, America Ferrera and Blake Lively — didn't need much prompting to deliver variations on the same theme, as they spoke to reporters along the denim-colored arrivals carpet.

The actors' message was clear: Guys and grown-ups may dig this, too.

More likely, however, it is young women who'll make or break "Sisterhood" at the box office. They're the ones who turned Ann Brashares' (search) 2001 novel into a best seller, which spawned two sequels.

The trilogy begins with four lifelong teen girls marking their first summers apart, only to return home a little older and a lot more worldly. A tie that binds them is a pair of jeans that somehow fits each woman perfectly, despite their varying shapes, sizes and style sensibilities.

Ferrera ("Real Women Have Curves (search)") acknowledged that the beloved book and film are two different creatures.

"For me, there is a such a beautiful kind of magic in the book that needed to be retained, and I feel like facts were changed but ultimately that same kind of feeling that you get when you read the book is there when you watch the movie," she said.

Author Brashares agreed, adding the sisterhood of actors mirrored the one in her novel.

"They really bonded, which is what you want," she explained. "I've seen them enough off-camera. I can see that (their friendship) has its own momentum now, which is a really nice thing for me to watch."

Lively, who's her feature-film debut, recalled one moment during a break in filming, when she and her co-stars got so embroiled in choreographing a dance to Vanilla Ice's "Ice Ice Baby," they ruined their hair and makeup and held up production for more than an hour.

Ken Kwapis, the film's director, was the only real leading man in a production with four leading ladies.

"A friend of mine said I must have been a teenage girl in a previous lifetime," he joked. "Although, to tell you the truth, I think I knew twice as much about women when I started the picture as I do now. Now they're twice as mysterious to me."