Dynamic path. HOW?!?!

How do i control a movie clip which path is contained in a variable?
I.E.: I have a variable called:
_root.activeButton

The variable has this path as a value:
_root.buttons.button1

Q: How do I tell _root.buttons.button1 to go to frame 1?

I think it is something like this, but I can’t remember exactly:
[_root.activeButton].gotoAndStop(1)