ENTOURAGE star Jeremy Piven insists the reason he had a falling out with John Cusack was because his longtime friend wasn't supportive of his newfound success. The two first studied acting at Chicago's Piven Theatre Workshop in Illinois, which was run by Piven's parents. Piven played supporting roles in many of Cusack's films, including SAY ANYTHING, Grosse Pointe Blank and Runaway Jury, before getting his big break on the hit US TV series Entourage and winning an Emmy Award. When asked how Cusack has handled Piven's recent successes, he tells America's Best Life magazine, "No comment. I mean, you could fill in the blank, I bet." Piven says of Cusack, "I was always proud of him, and I was always in his corner. Always. It just says so much about a person if he has space for other people's success. "I have always been so proud of my friends' success. I own that proudly because I come by it naturally. I was raised on that spirit of collaboration. "You start getting into trouble in life when you start comparing and contrasting your life to anyone else's."