Answer
Yes, Proof was involved in a number of solo projects. In 2005, he released his debut solo album, "Searching for the Perfect Beat". The album was a critical and commercial success, and spawned the hit singles "My Name is Proof" and "Nothin' But Trouble". Proof also released a number of mixtapes and EPs, and collaborated with a number of other artists, including Eminem, D12, and 50 Cent.