Cashner injured his right rotator cuff in his first major league start on April 5. He was put on the disabled list on April 8. During a rehab session on May 16, Cashner re-injured the rotator cuff and had not pitched competitively until last week. He is pitching out of the bullpen at Triple-A Iowa and is expected to re-join the Cubs sometime in early September.
Jackson, the Cubs's first-round pick of the 2009 draft and the organization's top prospect, is batting .319 with six home runs, 25 RBIs and six stolen bases at Triple-A Iowa. He split the 2011 season between Iowa and Double-A Tennessee.
LeMahieu is batting .316 overall between Double-A Tennessee and Triple-A Iowa. He hit .243 in 23 games with the Cubs earlier this season.
Lake is batting .281 with 12 home runs, 51 RBIs and 36 stolen bases overall this season in stints at Single-A Daytona and Double-A Tennessee.
Carpenter had a 2.79 ERA in 10 games with the Cubs earlier this season. McNutt is 5-5 with a 4.35 ERA in 22 starts with Double-A Tennessee.
Pitcher Jeff Beliveau is on the taxi squad, meaning he's eligible to play Wednesday and Saturdays.