I always thought that MSG was a flavor enhancer, not a meat tenderizer. The tenderizers I know are usually made from dried papaya or pineapple and just sprinkled on the meat and allow time for the enzymes to break down the meat fibers. The same result can be obtained by marinating meat in papaya or pineapple juice.
Thanks, CanMan. I thought I had read somewhere that the MSG would serve as a tenderizer in a pinch. I've not heard of using the pineapple or papaya juices. The pineapple juice will be easier for me to find in my town.