JC Tretter, former Cleveland Browns center, retires after 8 seasons in NFL but remains NFLPA president - ESPN
Former Browns center JC Tretter announces retirement from NFL
Tampa Bay Buccaneers confident that Rob Gronkowski will resign with the team - AS USA
49ers news: Alex Mack re-works his contract to free up $4 million in cap space as he mulls retirement - Niners Nation
Grievance filed by NFL says players' union leaders advised running backs to fake injuries - Alaska Highway News
Will Linsley and Tretter Battle at Center?
Former Packers, Browns lineman JC Tretter announces NFL retirement
Cleveland Browns news: Joe Thomas, Nick Chubb, Myles Garrett and more - Dawgs By Nature
J.C. Tretter: Breaking News, Rumors & Highlights
JC Tretter Retires from NFL at 31; Former Packers, Browns Center Is NFLPA President, News, Scores, Highlights, Stats, and Rumors
7-time Pro Bowl C Alex Mack retires after 13 years in NFL
Former Browns center JC Tretter announces retirement from NFL
JC Tretter Is Retiring from Football
'On to the next chapter': Former Cleveland Browns center JC Tretter announces retirement
Veteran NFL Player Announces Retirement at 31, Announces Future Plans