Mike Seaver will never forget his dad, Dr. Jason Seaver.

Hours after Alan Thicke's untimely death, his Growing Pains co-star and TV son Kirk Cameron paid an emotional tribute to the late star on social media.

"I spent Monday through Friday for seven important years with Alan Thicke as my 'TV dad.' I'm shocked and truly heartbroken today at the news of his death," Kirk, 46, wrote on Instagram. "Alan was a generous, kind and loving man. I am so blessed to have grown up with him. [My wife], Chelsea, and I send our love and prayers to his family tonight. We will cherish the memories… 'sharing the laughter and love.'"

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The two starred in the hit sitcom together from 1985 until 1992. Alan passed away from a heart attack on Tuesday, Dec. 13 at age 69. He will be missed!

Click through the gallery below to see the cast of Growing Pains then and now.