Prevent Restart of MCs which are Playing

Ok, so I have this clip I want to play when someone presses the “UP” arrow key but once it’s playing, I don’t want the user to be able to play it again. I wan’t it to finish playing first, before it is replayed using the UP key. The mc is in the second frame of my “Dude1” mc, and here’s my code thus far.

onClipEvent (enterFrame) {
if (Key.isDown(Key.UP)) { (2);

PS, How can I change the “Key.isDown” command for keys like A, B, C… or 1, 2, 3… ?