Chairman of the Nobel Committee Goeran Hansson announnces winners of the Nobel Prize in medicine at a press conference on October 7, 2013 at the Karolinska Institute in Stockholm. The 2013 Nobel Prize in Physiology or Medicine went to James E. Rothman, Randy W. Schekman and Thomas C. Sudhof "for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells," according to the Nobel Assembly. (Xinhua/Shi Tiancheng)

Pictures of the 2013 winners of the Nobel Prize in medicine James E. Rothman, Randy W. Schekman and Thomas C. Suedhof (L-R) are seen on a screen during a press conference at Karolinska Institutet in Stockholm, capital of Sweden. The 2013 Nobel Prize in Physiology or Medicine went to James E. Rothman, Randy W. Schekman and Thomas C. Sudhof "for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells," according to the Nobel Assembly. (Xinhua/Shi Tiancheng)

A picture of German scientist Thomas C. Suedhof and illustration of his work are displayed on a screen during a press conference at Karolinska Institutet in Stockholm, capital of Sweden, Oct. 7, 2013. The 2013 Nobel Prize in Physiology or Medicine went to James E. Rothman, Randy W. Schekman and Thomas C. Sudhof "for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells," according to the Nobel Assembly. (Xinhua/Shi Tiancheng)

A picture of US scientist James E. Rothman and illustration of his work are displayed on a screen during a press conference at Karolinska Institutet in Stockholm, capital of Sweden, Oct. 7, 2013. The 2013 Nobel Prize in Physiology or Medicine went to James E. Rothman, Randy W. Schekman and Thomas C. Sudhof "for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells," according to the Nobel Assembly. (Xinhua/Shi Tiancheng)

A picture of US scientist Randy W. Schekman and illustration of his work are displayed on a screen during a press conference at Karolinska Institutet in Stockholm, capital of Sweden, Oct. 7, 2013. The 2013 Nobel Prize in Physiology or Medicine went to James E. Rothman, Randy W. Schekman and Thomas C. Sudhof "for their discoveries of machinery regulating vesicle traffic, a major transport system in our cells," according to the Nobel Assembly. (Xinhua/Shi Tiancheng)