BERKELEY (CBS/AP) — Americans James Rothman and Randy Schekman and German-born researcher Thomas Suedhof won the 2013 Nobel Prize in medicine Monday for discoveries on how hormones, enzymes and other key substances are transported within cells.

The prize committee said their work has helped researchers gain a better understanding of a range of diseases including diabetes and disorders affecting the immune system.

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Schekman is at the University of California, Berkeley, and Suedhof joined Stanford University in 2008. Rothman is a professor at Yale University.

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Schekman said he was awakened at 1 a.m. at his home in California by the chairman of the prize committee and was still suffering from jetlag after returning from a trip to Germany the night before. He told The Associated Press, “All I could say was ‘Oh my God,’ and that was that.”

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