Party Poker No-Limit Hold'em, $ BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Hero ($50.30)
Button ($22.61)
SB ($24.85)
BB ($22.40)
UTG ($28.65)

Preflop: Hero is MP with K, J. SB posts a blind of $0.10.
UTG calls $0.25, Hero raises to $1.25, Button calls $1.25, 2 folds, UTG calls $1.

Flop: ($4.10) 4, 6, J (3 players)
UTG checks, Hero checks, Button bets $3.9, UTG folds, Hero ?????

And wahts the plan for the turn?