KK on the Button - What's the Play?

[Hooked on Fish]

Party Poker $215 Sunday Tournament.

Average Stack: $11,000
Largest Stack: $60,000
My Stack: $22,000
Blinds: 500/1000
280 out of 2,000 or so left - In the money starts at 220

I have KK on the button. I've been moved fairly recently so I don't have reads on anyone at the table.

EMP raises to 4,000, everyone folds to me. I call.

Flop comes 7/4/3 rainblow. EMP bets 4,000, what's my play from here?

Thanks