AKs 3/4 through the field in a Tournament....what to do?

Party Poker No-Limit Hold'em Tourney, Big Blind is t150 (10 handed) converter

UTG+1 (t9787)
UTG+2 (t3788)
MP1 (t2295)
MP2 (t6478)
MP3 (t4665)
CO (t510)
Button (t2400)
Hero (t4981)
BB (t2685)
UTG (t1188)

Preflop: Hero is SB with A[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/spade.gif[/img].
<font color="#666666">2 folds</font>, UTG+2 calls t150, <font color="#CC3333">MP1 raises to t475</font>, <font color="#666666">1 fold</font>, <font color="#CC3333">MP3 raises to t800</font>, <font color="#666666">2 folds</font>, Hero calls t725, 1 fold, UTG+2 folds,<font color="#CC3333">MP1 raises t1820 (All-In)</font>, MP3 calls t1495,

MP1 is LAG
MP3 has only been on the table for a few hands, no read as of yet.

Hero?? <font color="red"> </font>