Ryan Reynolds has paid tribute to ''incredible'' Michael J. Fox.

The 'Green Lantern' actor struck up a friendship with the 'Back to the Future' star - who suffers from Parkinson's disease - five years ago when he ran the New York marathon in aid of Michael's charitable foundation, and says his pal is ''unsinkable''.

He said: ''He's incredible in everything that he does, from the foundation to his work to his work ethic.

''There's a reason why everyone likes this guy so much - he's just unsinkable.''

Both Ryan and Michael were brought up in Vancouver, Canada, and the 'Croods' star says it has given them a ''shared connection''.

He said: ''I've gotten to know his family over the years and they're just amazing. They're just an incredible lot of people.''

''We have that connection - we're all from the same part of the world,''

The 37-year-old star's father also suffers from Parkinson's disease - which causes degeneration of the nervous system, often causing involuntary tremors and muscle spasms - and the actor is grateful for the help he receives from the Michael J. Fox Foundation for Parkinson's Research.

He told People: ''My dad's hanging in there. Like so many people who are afflicted with this disease, they have an incredible resource in this foundation ... They also have a reason for hope.''