Cameron Boyce's 'Descendants' co-stars pay tribute to him on his birthday

"Descendants" cast members are paying tribute to their late co-star Cameron Boyce, who would have been 21 years old today.

Honoring Boyce's passion for philanthropy, Dove Cameron teamed up with the Cameron Boyce Foundation to launch a new T-shirt campaign for its Wielding Peace initiative, aimed to fight gun violence.

Proceeds from the campaign will support The Cameron Boyce Foundation, and a portion of the profits will also be donated to The Actors Fund's COVID-19 Emergency Relief.

Cameron, 24, told People that the shirt's design -- a gun with flowers in the barrel -- was inspired by her tattoo, which she got earlier this year to remember Boyce.

"Cameron was a light," she told the magazine. "Every year on his birthday he did something to give back, and this year, The Cameron Boyce Foundation is honoring his legacy by continuing that tradition on what would have been his 21st birthday. I could not be more proud to support this cause for my friend, whom I miss every day."

"I am so honored to be a part of this incredible organization in support of my cherished friend, and I encourage everyone to please go and purchase it so that we can continue to advocate to end gun violence, fund epilepsy research and contribute to ending the global water crisis," Cameron added.

Boyce, who died last July after after suffering a seizure related to epilepsy, had been receiving treatment for the condition at the time of his death, and had not had a seizure in more than a year, his parents told "Good Morning America" last August. Epilepsy is a neurological disorder that affects 3.4 million people in the U.S., according to the U.S. Centers for Disease Control and Prevention (CDC). In recent essay for "GMA," Boyce's mother, Libby Boyce, called epilepsy, "the most common disease that we know the least about."

In addition to Cameron, "Descendants" stars Sofia Carson and BooBoo Stewart also shared sentiments about Boyce on his birthday.

"What I would do to hold you this tight today. But I know you're dancing in heaven," Carson wrote on Instagram. "Happy Birthday My Cam. I miss you, forever. I love you, forever."

Raising awareness about the T-shirt campaign, Stewart added: "Happy birthday man, love you."