You might also have to take COMLEX Step 1 too (in order to take Step 2 and 3).
In some states, in order to get licensed, you have to take the COMLEX if you're a DO graduate (and the USMLE won't be accepted as substitute). Some state don't care if you take USMLE or COMLEX, as long as you take all 3 steps. So you have to look into this.
I think the rule of thumb is if a state have seperate board of medicine and board of osteopathic medicine, they have seperate requirements for licensure ... but of course, there are exceptions