1.   Avonex is a genetically engineered copy of a naturally occurring protein.

2.   It works because becaplermin mimics platelet-derived growth factor, a naturally occurring protein in the body.

3.   Myotrophin is a naturally occurring protein that promotes the survival and regeneration of certain nerve cells.

4.   Studies reveal that a substance called human nerve growth factor, a naturally occurring protein, has beneficial effects on brain cells.

5.   The drug, osteoprotegrin or OPG, a genetically engineered version of a naturally occurring human protein, appears to regulate bone mass, according to Amgen.

6.   Angiostatin, a naturally occurring human protein, was thrust into the spotlight in May when it was featured in a front-page New York Times article.

7.   One of those is an anti-microbial agent, known as lactoferrin, that is a naturally occurring protein in the milk of mammals.

8.   TPA is a naturally occurring protein that dissolves clots.