The prison assault on Gotti is a rather poor example. The mob isn't a prison gang and has practically zero pull in prison, especially today. In fact, most mobsters are running away from prison into the arms of the Witness Protection Program, they're seen as the cowards in today's criminal world. Scarpa Jr. I believe was shelved, still again another poor prison example. I think for the most part though the no putting your hands on a made man rule is followed, so there probably hasn't been many killings over it.
The mob was powerful in certain prisons, not on a prison gang level but definitely strong enough to be not bothered by other inmates, Gotti was also respected in the prison the guy jumped him was mentally unstable and in the end they had to transfer him to another jail because Gotti put a contract on his head.
