Floria Sigismondi’s upcoming biopic about 70’s all girl rocker group, The Runaways, now has precocious Dakota Fanning aboard. Fanning is set to play 15 year old Cherie Currie who became best known for her over-sexualized look and drug abuse beginning at a young age. The home schooled starlet first came on the map as the adorable daughter to Sean Penn in I AM SAM, and has since taken off in ways even I couldn’t have forseen. Now she’s 15, and all grown up… maybe even a little too fast. We can expect that this is just phase one of Fanning’s “prove to Hollywood I’m a real actress” plan. Next thing you know she’ll be doing a movie with a rape scene…. oh wait. Fanning will be co-starring in The Runaways with Kristen Stewart, who’ll star as Joan Jett.