"Beastie Boys" rapper MCA -- real name Adam Yauch -- has died.
In 2009, MCA announced he was being treated for a cancerous parotid gland and a lymph node (below). He has since undergone surgery and radiation therapy.
So far, it's not clear if the death is related to the rapper's battle with cancer.
Russell Simmons' website GlobalGrind.com first reported the death. We have spoken to people independently connected to the rapper who also say he is dead.
MCA co-founded Beastie Boys in 1979 with Mike D, and Ad Rock ... and went on to churn out some of the most iconic albums in hip-hop ... including License to Ill, Paul's Boutique, Check Your Head and Ill Communication.
The group has won multiple Grammys and were inducted into the Rock and Roll Hall of Fame earlier this year.
The Beastie Boys haven't performed live since 2009.
MCA recently became a vegan at the recommendation of his Tibetan doctors.
The Beastie Boys' most recent music video was released last year for the song "Make Some Noise" -- and it stars a laundry list of A-listers, including Rashida Jones, Will Arnett, Rainn Wilson, Amy Poehler, Steve Buscemi, Kirsten Dunst, Zach Galifianakis, Orlando Bloom, Will Ferrell, John C. Reilly, and Jack Black.
Yauch is survived by his wife and daughter. He was 47.