What are the rule regarding grabbing the cage?

I am asking because I was re watching the Silva Sonnen fight and I noticed in the 4th round (4:40ish - right before Silva gets warned about the elbows) Anderson grabs the cage for balance and holds onto it as he throws a kick at Sonnen. Would this be considered an illegal move or cage grab or is it only when you are on the defensive?


It is quick and minor, not saying it had any effect on the outcome, but just curious if someone knows the details around the rules. Plus, we should have these rules on lock down with the Tito Evans fight tomorrow.