From the Lions site..
Tackle Jeff Backus has been activated off the Active/Non-Football Injury list and is currently practicing with the team. Tackle Isaac Sowells was released to make room on the roster for Backus.
Wide receiver Calvin Johnson, who did not play Friday at Cleveland, is also practicing along with fellow wide receiver Titus Young.
During individual drills, returner Stefan Logan took reps with the running backs while starting running back Jahvid Best did not practice.