Steelers activate LB Arnold Harrison

Outside linebacker Arnold Harrison is active for the first time this season. He replaces tight end Matt Spaeth on the Steelers' 45-man roster for today's game against the visiting San Francisco 49ers.

Spaeth is sidelined with a deep thigh bruise.

Also inactive for the Steelers are wide receiver Willie Reid, cornerback Ricardo Colclough, running back Gary Russell, linebacker Andre Frazier, guard/center Darnell Stapleton, offensive tackle Trai Essex and quarterback Brian St. Pierre.

Among the inactives for the 49ers is starting outside linebacker Manny Lawson. Lawson sustained a season-ending knee injury in practice last week.