I agree with Scotch: You should bet out here. More than likely, MP1 will raise, as most pre-flop aggressors will bet/raise the flop. This not only forces the players left to act after MP1 to call 2 bets cold, but when you 3-bet, you will force the players who called your inital bet on the turn to call 2 more bets (MP1's raise and your re-raise).