INDIANAPOLIS – Grover Stewart, one of the Indianapolis Colts’ defensive cornerstones, has been suspended for the next six games for violating the NFL’s performance-enhancing substances policy.

Stewart immediately accepted responsibility on his Instagram account, but that doesn’t lessen the severity of the discipline. The suspension is without pay, so he’ll forfeit six paychecks from his $9.285 million base salary. That’s $3.095 million.

The seventh-year defense tackle also is in the final year of a three-year, $30.75 million extension he signed in November 2020. He’ll be a free agent at the end of the season.

Stewart has started 70 of 102 games since being selected in the fourth round of the 2017 draft, and developed into one of the NFL’s premier tackles.

He’s eligible to return to the active roster Dec. 4 following the Colts’ week 13 game at Tennessee.

There was no comment from the team.

A six-game suspension under the league’s PED policy is the appropriate discipline when a player tests positive for an “anabolic agent’’ for a first time.

Stewart addressed the situation via his Instagram account. He indicated he unknowingly ingested a substance on the NFL’s banned list, which is no defense in the eyes of the league.

“I want to apologize to the National Football League, the Colts organization, my teammates, our fans and my family, Stewart posted. “I was surprised and disappointed to learn I had violated the policy. I respect the integrity of the game and would never purposely put myself or the team in this kind of situation.

“I am responsible for what I put in my body, and I should have taken the proper steps to educate myself. I will learn from this moving forward, and I will take the appropriate measures to ensure this never happens again.’’

Stewart and DeForest Buckner have formed one of the NFL’s premier tackle tandems since 2020. They have been the backbone of the Colts’ run defense.

The 6-4, 314-pound Stewart has 259 tackles, including 8.5 sacks and 27 tackles for loss. In six games this season, he ranks 8th on the defense with 20 tackles, including two for a loss.

Without Stewart, coordinator Gus Bradley must turn to Taven Bryan, Eric Johnson II, rookie Adetomiwa Adebawore and perhaps Tyquan Lewis to work alongside Buckner.

Stewart is the fourth Colt to be suspended by the NFL this season. He follows:

*cornerback Isaiah Rodgers Sr., suspended indefinitely for violating the league’s gambling policy.

*defensive end Rashod Berry, also suspended for violating the gambling policy.

*cornerback Chris Lammons, suspended for three games for violating the league’s personal conduct policy.

Rodgers and Berry were released shortly after the suspensions were announced. Rodgers signed with the Philadelphia Eagles.

Lammons was released Sept. 25, but was re-signed to the practice squad.

You can follow Mike Chappell on Twitter at @mchappell51.