The grad student I am working with: "proteins... sometimes they like to have other proteins around them because if there aren't any, they can get quite lonely. So when in doubt you should add some BSA and they'll be happier."

On another note, I got my Jacqueline du Pre DVD order in the mail! I've only checked out parts of it so far, but the video excerpts of her performing various parts of the Beethoven Cello Sonata in A -- it is sooo incredible. She has such a magical way of drawing all listeners/viewers into her performance. A trip to a cello rental store this weekend is definitely in order :)