Are you asking about the Russian mob in USA or in Russia?

In Russia, there have been rats in the mob all the time. Just to make a recent example, in the city of Kirov there have been arrests of the members of the "Prokoposkaya" gang. The boss is Mikhail Prokopyev, and his right-hand man Sergei Krivoshein ratted on him for the 2003 murder of the businessman Anatoliy Gorbushin.

Also, several years ago, a prominent associate of the Tambovskaya gang in St.Petersburg, Badri Shengelia, ratted on his bosses, including the n.1 of the gang, Vladimir Kumarin.

As for how they are dealing with rats, it depends on how much the police wants to protect them. If the order to jail a specific gang comes from Moscow, even directly from Kremlin, then touching a turncoat is suicide. But in regions that don't attract attention of the central power and all the police is bought and under control, then nobody even thinks of turning informant.

At least that's the impression I currently have, but I haven't been in Russia for years.

Willie Marfeo to Henry Tameleo:

1) "You people want a loaf of bread and you throw the crumbs back. Well, fuck you. I ain't closing down."

2) "Get out of here, old man. Go tell Raymond to go shit in his hat. We're not giving you anything."