From Wikipedia

DeShaun Dupree Holton (October 2, 1973 – April 11, 2006), better known by his stage name, Proof, was an American rapper from Detroit, Michigan. During his career, he was a member of the groups Goon Squad, 5 Elementz, Promatic, and most notably, D12. He was a close childhood friend of rapper, Eminem, from the time that both were 14 years old; although the pair attended different schools they lived on the same block. In 2006, Proof was shot and killed during an altercation at the CCC nightclub in Detroit.

Early career

Under the moniker, “Proof”, Holton first rose to national prominence as a part of the rap group, D12, a hip-hop group he was instrumental in forming; although he had achieved a degree of success prior to its formation. He was featured in The Source’s “Unsigned Hype” column in 1999 and came close to winning the 1998 Blaze Battle. His first television appearance was in the video for Aaliyah’s “Age Ain’t Nothing But a Number”. In 2000, Proof toured with Eminem, Dr. Dre and Snoop Dogg in the Up In Smoke Tour, performing as a hype man for Eminem. He gained further exposure in 2001 with the release of Devil’s Night, D12′s debut album on Interscope Records. The following year, Proof collaborated with Dogmatic on “Promatic” and joined Eminem’s “Anger Management” tour in support of the release.[1] He appeared in the film, 8 Mile, along with Eminem and Xzibit; although, in the film, the character he was the basis for, Future, was portrayed by Mekhi Phifer. Proof instead played Lil’ Tic, a freestyle rapper who rap battles the lead character, B-Rabbit, played by Eminem.[2] To capitalize on the publicity from the film, Proof released a six-song EP called Electric CoolAid: Acid Testing.[3] Proof also starred in a cameo role, alongside the rest of D12, in The Longest Yard, appearing as “Basketball Convicts” during the credits