The Chicago Bears boosted their defense by agreeing to a four-year contract with Super Bowl champion linebacker Danny Trevathan on Wednesday.
Trevathan's signing was the first in a flurry of moves announced by the Bears shortly after the opening of free agency.
They also signed cornerback Tracy Porter and Arizona Cardinals right tackle Bobby Massie to three-year contracts. Backup running back Jacquizz Rodgers and offensive tackle Nick Becton also re-signed, agreeing to one-year deals.
Trevathan, 25, was the leading tackler on the league's No. 1 defense. He is leaving the Broncos for a team that won only six games but showed improvement in its first year under coach John Fox and General Manager Ryan Pace.
Looking for a receiver to replace the retired Calvin Johnson, the Lions agreed to a five-year contract with free agent wideout Marvin Jones.
Jones caught 65 passes for 816 yards and four touchdowns last season for Cincinnati.
Green Bay reported no moves Wednesday.