I think the fact that the button called your lead out on the turn indicates he probably has your pair of 4s beat and I would doubt you're getting him to laydown. If you thought you were ahead on the turn or you just wanted to put maximum pressure on him then I think a check raise would get the job done much more often than a lead out. A check raise indicates more strength than a lead out here and it ends up costing you less overall. If the button comes back over the top and says he's stronger I think you can laydown safely knowing that you are beat and still have chips in your stack to play with.