Alicia Keys and Rihanna are rallying their fans in an attempt to locate a bone marrow donor for 11-year-old Broadway performer Shannon Tavarez.

Tavarez -- who recently played the role of young Nala in The Lion King on Broadway -- was diagnosed with an acute form of leukemia after investigating mysterious pains in her legs, which made it difficult for her to walk or perform. Keys visited Tavarez in a Long Island hospital on July 2, and told People that she was she hoped for the young actress and patients in similar situations to "grow up to live their dreams." "For her, the sky is the limit, but now she's fighting for her life," Key said.

Rihanna, a longtime supporter of DKMS America -- the world's largest non-profit marrow donor center -- stressed the importance of taking the time to register for the cause. "[Tavarez] should be performing on Broadway, but is confined to her bed, fighting for her life," Rihanna told People. "She needs to find a bone marrow donor to survive. I urge all my fans to register [as donors]. It's the most beautiful thing someone could do, to give the gift of life."

Fans who want to become donors are urged to visit DKMS Americas or The National Marrow Donor Program.

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