PokerStars No-Limit Hold'em, $0.50 BB (6 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

MP ($143.10)
CO ($53.40)
Button ($56.70)
Hero ($78.50)
BB ($50)
UTG ($98.35)

Preflop: Hero is SB with A, J.
1 fold, MP calls $0.50, 2 folds, Hero raises to $2.5, 1 fold, MP calls $2.

Flop: ($5.50) K, 4, A (2 players)
Hero bets $4, MP raises to $8, Hero calls $4.

Turn: ($21.50) 7 (2 players)
Hero checks, MP bets $15, Hero ???

---

I have only limited stats on Villian, he is about 80/25/14 over 13 hands so far. We've only tangled once so far, when I took down a moderate sized pot with my set of tens versus his two pair.

What's your move here?