Value bet with posible straight on the board?

[Jimbo720]

Party Poker 2/4 Hold'em (7 handed)

Preflop: Hero is CO with 9/images/graemlins/spade.gif, 9/images/graemlins/heart.gif.
UTG folds, MP1 calls, MP2 calls, <font color="CC3333">Hero raises</font>, Button folds, SB calls, BB calls, MP1 calls, <font color="CC3333">MP2 3-bets</font>, Hero calls, <font color="CC3333">SB caps</font>, BB calls, MP1 calls, MP2 calls, Hero calls.

Flop: (20 SB) J/images/graemlins/club.gif, 9/images/graemlins/club.gif, 4/images/graemlins/diamond.gif <font color="blue">(5 players)</font>
<font color="CC3333">SB bets</font>, BB calls, MP1 calls, <font color="CC3333">MP2 raises</font>, <font color="CC3333">Hero 3-bets</font>, SB calls, BB calls, MP1 calls, <font color="CC3333">MP2 caps</font>, Hero calls, SB calls, BB calls, MP1 calls.

Turn: (20 BB) Q/images/graemlins/heart.gif <font color="blue">(5 players)</font>
SB checks, BB checks, <font color="CC3333">MP1 bets</font>, MP2 calls, <font color="CC3333">Hero raises</font>, SB calls, BB calls, MP1 calls, MP2 calls.

River: (30 BB) 5/images/graemlins/spade.gif <font color="blue">(5 players)</font>
SB checks, BB checks, <font color="CC3333">MP1 bets</font>, MP2 calls, Hero...</font>
Final Pot: 34 BB

MP1 leading out on the turn when the possible (but unlikely) straight hit, and then leading on the the river after I had raised scared me. Who knows what party playas call down with. What should be done in this situation?

[J.R.]

I would raise the river because MP1 did not 3-bet the turn when nearly closing the action, which I would expect a straight to do (unless he's real crafty and thinks you have set and wants to 3-bet given the river didn't pair the board, counterfit his hand or complete a flush, but that's a bit much to attribute to an unkown party 2-4er). Its also possible MP1 has two pair and wanted to see if the river completed a draw or paired the board.

[challenger84]

Raise the river. MP1 most likely has some junky two pair.

[devinthedude]

I think you can probably raise here. MP2 probably has Q9 or QJ. I suppose at party 2/4 he could have KT, but the stop n go leads me to think 2-pair. MP2 probably has AA. I think you can rule out JJ or QQ based on the turn action. Cant really figure out what SB has, but I think most of the time you will raise and MP1 will show you Q9 or QJ in this game.