(AP) – More than 4,000 people have registeredfor this weekend’s Dempsey Challenge to raise money for a centerthat helps families cope with cancer. It’s the second year of the fundraiser, started by “Grey’sAnatomy” star Patrick Dempsey. He’s from Buckfield. He launched the challenge last year with a bike ride to raisemoney for the Patrick Dempsey Center for Cancer Hope & Healing atCentral Maine Medical Center in Lewiston. This year’s event has been expanded to two days. There will bewalking and running events Saturday and bicycle rides throughcentral Maine between 10 and 100 miles on Sunday.