Mountcastle (hamstring) was reinstated from the 60-day injured list Friday, Roch Kubatko of MASNSports.com reports.
Mountcastle will make his first MLB appearance since May 30, when he sustained a Grade 2 hamstring strain. He'll DH and bat fifth Friday. Colton Cowser (concussion) and Tyler O'Neill (wrist) were placed on the injured list in corresponding moves.