Who was the movie hustle and flow made about?

This movie was NOT about FIFTY CENT! Hustle and Flow was not about anyone. It was a Fiction movie, all characters therein were fictional characters. However; the main track in the movie HARD OUT HERE FOR A PIMP was written by 3-6 Mafia, with Taraji P. Henson singing actual vocals on the Grammy winning song's well known hook...."ya know, it's hard out here for a pimp; when you tryin' t' get this money for tha rent"...This movie starred Terrance Howard, Taraji P Henson, Anthony Anderson, Dj Qualls, And Taryn Manning.