NL50: AK in BB

[Foodchain]

MP is TAG and has done nothing unusual as far as I can tell from 30 something hands.

Party Poker - No Limit Hold'em Cash Game - $0.25/$0.50 Blinds - 6 Players - (LegoPoker Hand History Converter)

SB: $94.65
Hero (BB): $44.57
UTG: $59.31
MP: $106.26
CO: $50.57
BTN: $51.53

Preflop: Hero is dealt A[img]/images/graemlins/diamond.gif[/img] K[img]/images/graemlins/diamond.gif[/img] (6 Players)
UTG folds, <font color="red">MP raises to $2.00</font>, 2 folds, SB calls $1.75, <font color="red">Hero raises to $8.00</font>, <font color="red">MP raises to $15.00</font>, SB folds,

Hero ?