How common is it for mob families to recruit gangs to do their dirty work such as killings and extortion in today's era of organized crime?

I would imagine its easier for mob bosses in today's climate to get gangs to do this type of stuff for them and give them a cut of $$$ for agreeing to do it than to have one of their own soldiers have to do it and risk going to prison. I imagine that in every major city you have a mob family that has a business relationship with a major gang when it comes to certain matters that need to be taken care of.

Thoughts?