Alex Trebek's cancer diagnosis prompts outpouring of support

Following news that Alex Trebek has been diagnosed with stage 4 pancreatic cancer, celebrities and former "Jeopardy" contestants took to social media to share messages of support for the longtime "Jeopardy" host.

"Wheel of Fortune" host Pat Sajak

"Wheel of Fortune" host Vanna White

"Jeopardy" champ Ken Jennings

Walt Disney Company CEO Bob Iger

Dr. Phil McGraw

Canadian Prime Minister Justin Trudeau

Dr. Oz

Ken Jeong

David Muir

Chris Harrison

Recent "Jeopardy" contestant Brad Rutter

Children's television program "Arthur"