Gangland criminal Daniel Kinahan is taking a step back from his boxing business due to "bad publicity" his business partner has said.
Ex-fighter Matthew Macklin, who has no involvement in crime, has revealed Kinahan's new backseat role in the organisation as the gym undergoes rebranding.
The Marbella gym, established four years ago, now manages more than 100 fighters.
"Me and Daniel started off MGM. We were best friends and like I said I was over there all the time when I was training... so we set that up and it just grew from there," he said.
"Obviously then there's been a lot of bad publicity... Daniel has taken a backwards step.
"He still advises lots of fighters."
The Regency Hotel shooting last February happened during an MGM weigh-in event. Gunmen stormed the family hotel in the early afternoon, killing David Byrne.
The boxing gyms will now be known as MTK - Mack the Knife - Gym.
It comes after a back and forth with the MGM resorts in Las Vegas Macklin said in an interview with IFLTV.
At the beginning of the enterprise he said he joked that they would know that they had made it if it drew attention from the MGM in Vegas.
"[We said] If we get to the stage where the MGM casino in Las Vegas has heard about us we know that we have achieved more than our wildest dreams," he said.
Macklin said MTK Gym argued with MGM and "didn't go down without a fight", and have been allowed to keep some elements of their branding.