This weekend, the long-anticipated film version of Rock Of Ages hit theaters. The movie celebrates some of rock music’s biggest hits of the ’80s, with classics from Foreigner, Night Ranger and Twisted Sister’s songs making the film.

So, some may have been surprised when R&B superstar Mary J. Blige was cast as Justice Charlier, the owner of The Venus Club.

She sings a number of songs in the film, including Quarterflash’s “Harden My Heart”; she also appears on group versions of Poison’s “Every Rose Has Its Thorn” and Journey’s “Don’t Stop Believin’.”

Def Leppard’s Phil Collen says that Blige is such a great vocalist, that she can tackle any kind of music… and she was a great choice for the film.

Blige has had some other rock and roll moments: She covered Led Zeppelin’s “Whole Lotta Love” and “Stairway To Heaven” (both are available on iTunes) she also recorded a new version of U2′s “One” backed by U2 (it’s on her 2005 album The Breakthrough), and did a live duet version of “I Guess That’s Why They Call It The Blues” with Elton John (for his live album One Night Only from 2000).

–Brian Ives, CBS Local