Honestly i think the flop call is a little bit questionable.
With it being 2 bets back to you, you are only getting 13.5-1. At this point it seems like you are behind and drawing. (MP3 has a bigger pair) Not only that, but I think there is a good chance you are drawing almost dead.(to a straight) On a flop like this, in a big pot, and in your position i would just check and see what happens behind me. depending on the action it might be correct to check raise (if the bet comes from your immediate right, which it did) just check call (if a player on your left bets and everyone just calls you can call and try for a check raise on a good turn card) or in some cases check fold.

On the river i would just check call given the turn action. if you are lucky the player has a smaller set, however he probably has the nuts.