POP EYE

MACK MOGUL: The latest rapper to move into cinema is L.A.’s Mack 10, whose “Thicker Than Water”--with Mack as star, producer, writer of the original story treatment and financial backer--began filming last week. And though it’s his first time out, he says he’s ready to challenge all the competition--including his pal Ice Cube.

“I put my money and my word on it that this is the best [hip-hop movie] ever made,” he says.

His story, which he had screenwriter Ernest Brown put into script form, involves rival inner-city gangsta chieftains (played by himself and fellow rapper Fat Joe) who are unaware that they’re actually half brothers until they meet up at the funeral of their common father.

Mack says that he would have been happy to start off by acting in someone else’s film, but “I didn’t think nobody would put me in one, so I had to create my own opportunities.”

Meanwhile, he is finishing up a new album, “The Recipe,” with guest appearances by Cube, Snoop Doggy Dogg, Master P, Ol’ Dirty Bastard, Foxy Brown and others. Among the tracks is a duet with Gerald Levert and a version of the Clash’s “Should I Stay or Should I Go” featuring the rock band Korn.

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MOVIE-OLA: Michael Keaton, rocker? That was the challenge for Trevor Rabin, the former Yes member who had the job of helping the actor do a convincing job as leader of a struggling band for the upcoming movie “Frost.” But Rabin, who has just completed the score music for “Armageddon,” says the gig was surprisingly easy.

“Michael has been great,” Rabin says. “He responded to the task as far as being a rock ‘n’ roll singer. It can be so cheesy in movies and the last thing we wanted was the Partridge Family.”

Among the methods Rabin employed was to have Keaton write his own lyrics to some of the songs. Rabin then assembled a band to perform the material and appear in the film, a story about the Jack Frost character in a contemporary setting.

“Originally they had us set to rehearse in one of those plush facilities that a successful band like Yes would be in,” Rabin says. “But this was supposed to be about a band not being successful, so I found one of the urine-infested places beneath the Santa Monica Freeway instead. Michael looked at me like I was crazy, but I said this is what it would really be, and he said, ‘Great.’ He was so focused onto getting into character.”