Stephen Rothman, Ph.D., has been an experimental biologist for 40 years. He was a research professor at Harvard Medical School until 1971 when he joined the faculty at the University of California, San Francisco. Best known for his landmark studies of the transport of protein molecules across cell membranes, he has made notable contributions in everything from molecular biology to physiology. Dr. Rothman has published nearly 200 articles in "Nature, Science, "and other prestigious scientific journals.