Ticket sales for R-rated films have plummeted since movie theaters, bowing to political pressure, began tightening their enforcement of age restrictions, the Washington Post reported Thursday, citing a study by research group MarketCast. The study concluded that "significant numbers" of children under 17, especially girls, were being deterred from seeing R-rated movies. The theaters' policies, the study said, caused the recent releases The Mexican, starring Julia Roberts and Brad Pitt, and Angel Eyes, starring Jennifer Lopez, to lose a major share of the audience that ordinarily would have been attracted to them, the study said. It estimated that the movie Tomcats, from Joe Roth's Revolution Studios lost 30 percent of its potential audience because of theater enforcement of age restrictions. "I think the implications are that studios will take a hard look at movies that could be cut to be PG-13," Michael Schwartz, research director at MarketCast, told the Post. "They'll ask whether the R-rated scenes will gain them enough appeal to offset the losses, especially where there is strong teen interest." Indeed, Roth told the newspaper that he would never make a movie like Tomcats again. "This is material that's mostly innately appealing to 12- to 16-year-olds, so you're really stuck."