saving mp3's in Soundtrack Pro

When I open an existing mp3 in Soundtrack Pro, do some editing on the song, and then attempt to save the changes, again as an mp3, I am unable to do so for some reason.

When the track is first opened, Soundtrack Pro automatically decompresses the mp3, and I am seemingly unable to compress it back to an mp3 when the song editing is done.

My choices under the Save As menu in Soundtrack Pro are: audio file project / AIFF / WAVE/ NeXT / Sound Desinger II / QuickTime Movie.

Where is the mp3 option under the Save As menu?

Thanks for any tips!

just save it as an aiff and convert it to mp3 in itunes. its a simple solution if you are unable to export as an mp3 in the program itself

Right. It's too bad, though, that Soundtrack Pro does not have the ability to save files in MP3 format.
Quite surprising, actually...