Coulier recently began chemotherapy.

Decades after TV sitcomFull Houseended, costars Dave Coulier andJohn Stamosare more like family.

“You’re handling this with so much strength and positivityit’s inspiring.

John Stamos and Dave Coulier are longtime friends

John Stamos and Dave Coulier are longtime friends.Disney/Chris Willard

I love you.”

After testing, the prognosis was grim.

This has been a really fast roller coaster ride of a journey."

Disney/Chris Willard

When Coulier made his announcement,Stamos quickly offered his support.

“My brother from day 1,” he posted alongside photos of the two over the years.

“Love you @dcoulier and I’ll be by your side through it all.”