In two seasons as a backup in Chicago, Bush rushed for 608 yards and eight touchdowns on 177 carries while appearing in 28 games with one start. Last year the 6-1, 245-pounder ran for 197 yards and three TDs on 63 attempts.
Bush signed with the Bears in 2012 after spending his first four NFL seasons with the Raiders. In Oakland, he appeared in 61 games with 16 starts, rushing for 2,642 yards and 21 TDs on 632 carries. His most productive season was in 2011 when he ran for 977 yards.
Bush entered the NFL with the Raiders in 2007 as a fourth-round draft pick from Louisville. He spent the entire 2007 season on the physically-unable-to-perform list due to a leg injury.