Stapleton (6-3, 305) started the final 12 regular-season games and all three playoff games in 2008 after former starter Kendall Simmons suffered a season-ending injury. Stapleton, who was originally signed as an undrafted rookie free agent in 2007 out of Rutgers, played in every game last season after being inactive for every game his rookie season.
The Steelers also released wide receiver Steven Black, wide receiver Martin Nance, safety Derrick Richardson and center Alex Stepanovich to trim their roster to 75 players. The club must get their roster down to the league limit of 53 players by 6 p.m. on Saturday, Sept. 5.