Johnson, an 11-year veteran, has been suspended without pay for the team's next four games for violating the NFL policy on performance enhancing substances. The NFL announced the suspension Friday.
Johnson's suspension begins immediately. He's eligible to return to the Panthers' active roster on Dec. 25.
Panthers coach Ron Rivera said the suspension is disappointing.
He said Julius Peppers will start in Johnson's spot and Bryan Cox Jr. will work into the defensive line rotation.
Johnson released a statement through the team's website saying he accepts full responsibility.
"I accept full responsibility," Johnson said in a statement. "I have been recovering from back surgery, dealing with the daily grind of football and mistakenly thought this could help. It was an error in judgment on my part. We have a special group here I wanted to be a part of and felt an obligation to do my part by getting back as soon as possible. I have always prided myself on being a person who does things the right way through hard work, dedication and sacrifice. I want to apologize to my team, (owner) Mr. (Jerry) Richardson and Panthers fans for this mistake. Regretfully I have disappointed people, but I promise to come back ready to redeem myself when this suspension is over."
It's the first time Johnson has been suspended.
Wide receiver Damiere Byrd, who has spent the last eight games on injured reserve, will take Johnson's spot on the 53-man roster. Byrd is expected to help fill the void left by wide receiver Curtis Samuel.
The Panthers were already dealing with the prospect of being without a few starters against the Saints.
Rivera has still not made a decision on whether running back Christian McCaffrey (shoulder), Greg Olsen (foot) and linebacker Thomas Davis (hamstring) will play against the Saints while recovering from injuries. Those could be game-time decisions.
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