Photo: Julie Piekarski Probst/Instagram

Philip McKeon

Forty years later,Julie Piekarski Probststill remembersPhilip McKeon‘s toothy grin and kind heart.

Speaking to PEOPLE, Piekarski Probst — who starred in the beloved 1980s sitcomThe Facts of Life, briefly alongside Philip’s younger sisterNancy McKeon— shares some of her fondest teenage memories of growing up in Hollywood with Nancy and Philip, whodied on Dec. 10at age 55 after battling a longtime illness.

When they first met, Philip was starring in the CBS sitcomAliceasLinda Lavin‘s son, Tommy, and Piekarski Probst, now 56, was a Mouseketeer on the Mickey Mouse Club. She would go on to be cast as Sue Ann Weaver onThe Facts of Life.

“At the time, in Hollywood, certain age kids would kind of hang together a little bit, because you want to have socialization,” she says. “I just remember [Philip and Nancy] as good people — good, kind, honest, dedicated people. And I could relate to that coming from the Midwest. We just all clicked really well.”

“I remember being at their house a couple of times, I believe it was in Burbank,” she adds. “And Philip and I went out a few times, we enjoyed each other’s company.”

Piekarski Probst, who has not kept in touch with the McKeons in recent years, remembers young Philip as being “very genuine.”

“He had a great laugh and that big smile,” she says. “I’m going to use the word adorable because of his personality. You can say someone is handsome — and he was, he was cute to look at — but his personality came through.”

“He was very personable and down to earth — never put on airs,” she adds. “Very humble, and very authentic. They were what-you-see-is-what-you-get kind of people.”

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Nancy and Philip McKeon

AfterAliceended in 1985, Philip made periodic acting appearances before moving on to radio. He worked in the news department at Los Angeles station KFWB News 98 for 10 years, then moved to Wimberly, Texas, where he hosted his own radio show.

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Nancy McKeon and Philip McKeon

A source told PEOPLE that Nancy is“devastated”over her brother’s death.

“She and Philip werevery, very close,” the source said. “The whole family is going to cling together and find comfort in each other during this time. My heart goes out to them.”

source: people.com