It's been 10 years since High School Musical debuted on the Disney Channel, but it looks like the cast is still super close.

Zac Efron turned 29 years old on Tuesday, and his co-star, Ashley Tisdale, celebrated by sharing a super cute photo of the two together.

"Happy birthday buddy! @ZacEfron you will always be the Troy to my Sharpay," Tisdale sweetly wrote alongside a pic of Efron giving her a piggyback ride, referencing their High School Musical characters. "[Heart emoji] you brother!"

WATCH: Zac Efron and Vanessa Hudgens' Original 'High School Musical' Auditions Are Beyond Adorable

Monique Coleman (Taylor) also Instagrammed a cute throwback of Efron and herself on his special day, writing, "Happy Birthday @zacefron. I'm always proud of you, always rooting for you & eternally grateful for all the memories. I hope your last 20 is your best yet! Xx."

Although Efron's HSM boys have yet to publicly wish him a happy birthday, the Neighbors 2 star made it clear earlier this month that he, Corbin Bleu (Chad) and Lucas Grabeel (Ryan) are still in touch, when the three reunited at Bleu's Broadway debut in Holiday Inn.

"#Theboysareback," Efron tweeted alongside a black-and-white selfie of the trio.

In May, Efron delighted fans with a throwback pic with Tisdale, Bleu, and his ex-girlfriend, Vanessa Hudgens.

"So grateful I came across this picture … With the o.g. crew during one of the most cherished and exciting times of my life. Love you guys forever," he captioned the snap.

PICS: EXCLUSIVE: 'High School Musical' Turns 10! Cast Reflects on Surprise Disney Smash

ET spoke with Tisdale in January about the cast's close friendships.

"I just love that we all still love each other and love hanging out with each other and have that connection, you know?" Tisdale told ET exclusively. "It was a really special moment in our lives."

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