Dr. Mark Stacy, vice dean for clinical research at Duke University School of Medicine, remembers his special friendship with Muhammed Ali. Dr. Stacy served as the director of the Muhammad Ali Parkinson Center in Phoenix from 1998 – 2003.
"When I woke up and heard the news that he'd passed away, I thought, 'I have so many happy memories with Muhammad and his family that I'll try to think of those,' " Stacy said.