What about s'agir? I have come across it a few times in a context that sounds like être

S'agir means to be a matter of or to be about (something). 

Il s'agit de = it's a matter of, it's about 

You could replace it with c'est or even c'est a' propos de in many cases, though not all. But s'agir could be used when you want to be more precise about your subject. 

It's essentially interchangeable with c'est une question de, meaning it's a question of.