PREVIEW

Earlier this month, the Full House actor - known for playing Joey Gladstone on the sitcom, revealed he had been diagnosed with a "very aggressive" form of non-Hodgkin lymphoma and was undergoing chemotherapy treatments. And on Monday, John took to Instagram to share a photo of himself wearing a bald cap and using an electric shaver on the 65-year-old's head to show "solidarity" with his long-time friend. "Nothing like throwing on a bald cap and flexing some Photoshop skills to show some love and solidarity with my bro @dcoulier. You're handling this with so much strength and positivity - it's inspiring..."