Whats my play?

[Slappz]

Party Poker No-Limit Hold'em, $ BB (6 max, 5 handed) FTR converter on zerodivide.cx

BB ($232)
UTG ($207.19)
MP ($260.10)
Hero ($393.50)
SB ($266.50)

Preflop: Hero is Button with A[img]/images/graemlins/spade.gif[/img], Q[img]/images/graemlins/club.gif[/img]. SB posts a blind of $2.
1 fold, MP calls $4, Hero raises to $15, 2 folds, MP calls $11.

Flop: ($36) K[img]/images/graemlins/spade.gif[/img], 2[img]/images/graemlins/club.gif[/img], 5[img]/images/graemlins/club.gif[/img] (2 players)
<font color="red">MP bets $15 </font>, Hero???

Anyone have a line to take here?
Villians bet could mean anything from set to underpair, or some kind of combo draw.