American Andrew Fire reacts while being interviewed at Stanford University in Palo Alto, California October 2, 2006. Fire and fellow American Craig Mello won the 2006 Nobel prize for medicine on Monday for their discovery of how to switch off genes, a potential road to new treatments for diseases from AIDS to blindness and cancer. REUTERS/Kimberly White (UNITED STATES) Also refer to image GF1DUCDNUAAA