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Jason Momoa is continuing to call on his fans to make a change.
The actor, 42, shared a post on Instagram Friday, where he pled with his followers once more to become potential donors to the Be The Match Registry, a national marrow donor program, amid his friend Travis Snyder's cancer battle.
"Aloha everyone," Momoa began in a video, which sees him posing shirtless in a field. "As you've seen lately, I've been talking about my friend Travis who has been fighting cancer for a third time, and how important it is that we raise the stem cell registry for him and the thousands of others who need matches."
"First off, I just wanted to say thank you very much [to] everyone who's been getting involved. I've seen it, it's beautiful, and we're starting to make an impact, so, please, let's keep it going," the Aquaman star continued.
Added Momoa: "We can all make a change together. Please join the registry. All you have to do is swab your cheek and save someone's life. Be a hero — a real hero."
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Momoa reiterated his statement in the caption of his post. He also shared photos of Snyder's three kids — Hank, Miles and Luke — in his slideshow, detailing how their father "needs a match."
"I love these boys," Momoa wrote alongside a photograph of Snyder and his three sons. "They've watched their dad battle cancer for 7 years. His only hope for a cure now is to find a match in the registry. Please help them and thousands of others."
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Momoa shared the same posts on his Instagram Story as well, alongside a video from his PEOPLE interview with Snyder from last month.
The star also included a note about how "Only 2% of the population is on the stem cell registry, which means cancer patients die waiting for a match. Every day."
In late May, Momoa called for more "heroes" of the world to step up and help Snyder in his fight against acute myeloid leukemia, which he was diagnosed with in 2015. The illness is a type of cancer in which the bone marrow makes a large number of abnormal blood cells — the most common type of acute leukemia in adults — according to the National Cancer Institute.
It can be treated with a blood stem cell transplant, which replaces unhealthy blood cells, but Snyder initially didn't have any full matches in the Be The Match Registry. He underwent chemotherapy, which put his cancer in remission. Since then, the husband and father-of-three has relapsed three times, most recently in March, which has left him seeking a donor once again.
"[When I was first diagnosed] you get dealt the worst card of leukemia and then you don't have a match. It was really hard," Snyder previously told PEOPLE. "Throughout all of this, I think about my kids. Each relapse has been the hardest conversation to have with them. I just want to be able to keep raising these boys."
Snyder also praised Momoa for standing by his side and offering to help in any way. "Some of my friends kind of shrink when you're in trouble, or it becomes kind of surface-y," he said. "And Jay was just right there again."
Momoa, who aged out of being a donor candidate, has since vowed to use his platform to encourage others to join the registry in case they are a match for someone in need. "I'm supposed to be a superhero," the actor told PEOPLE. "And you think, 'God, Anyone at any time, if you're just a part of the registry, you have an option to save a life.'"